uvantha vuLLaththanAy ulakamaLanthu aNdamuRa
nivarntha neeNmudiyan anRu nErnthanisAsararaik
kavarntha venkaNaikkAkuththan kadiyArpozhil arangaththammAn arais
sivanthavAdaiyinmEl senRathAmenasinthaniyE

Meaning:
My Lord who with a happy mind, measured all (three) worlds, by growing as tall as the heavens, with a crown that reaches the heavens, who once as Rama took the lives of the opposing asurAs using fierce arrows, and who now rests in arangam of the fragrant forests, upon Him my mind has settled.

Essence:
In the first song, thiruippANAzhvAr talked about emperumAn coming after him - His feet on their own came and glowed inside AzhvAr. In this song, AzhvAr talks about how his mind not settling for His feet alone is now pushing AzhvAr to go after His dress (vanthunathadiyEn manampukunthAy pukunthaRpin vaNangum en sinthanaikkiniyAy).

A cow that has given birth to a calf, realizes that the calf does not know her scent and pushes the calf toward her udder. Once the calf catches on to the mother's scent, it will on it's own return to the mother. Thus, emperumAn's feet had to go AzhvAr (in the first song); once that happened, AzhvAr's mind returned on it's own to Him.

How did AzhvAr's mind which started at the feet end up on the dress (thiruppariyattam)? When one's mind is on to a sweet thing, it does not settle for one sweet thing alone. It's passion for the sweet thing grows.

Compare to a piece of wood caught in the ocean near a beach. It does not come back to the beach immediately; instead, it climbs from one wave to the other, and tries measure the entire ocean. Such is the state of thiruppANAzhvar's mind.

uvanthavuLLathan - Emperuman's mind is happy because His feet ended in AzhvAr's mind (eyes). It is us who should be delighted that His feet are on our head (when He measured the worlds). Yet, His mind is happy like that of a mother who delights in her child getting milk to drink.

sri dEsikar's comment: indrA and other dEvAs begged emperumAn to retrieve their lost kingdom from mahAbali; with great affection for them, He went to mahAbali and instead of destroying him asked him for land and showed his anugraham even to him. He also showed his anugraham to prahalAda even though he was born in the asura tribe. Thus He shows His affectionate heart toward everything. Here sri dEsikar is using the phrase as ug(v)antha uLLaththanAy.

ulakamaLanthu - Without differentiating anyone, He put His feet on everyone's head. Thus, both the Bhakthas and the sinners ended up living as equals. While the asurA mahAbali thought he had given a limited amount of land, He measured all the (limitless) worlds.

andamuRa - His swaroopam reaches the entire universe (grew to the heavens).

nivarntha - Flowering.

neeNmudiyan - The high point for the crown is being that even for the other world. ubayavibhoothi nirvAhagaththvam is brought out here.

sri dEsikar's comment: by defining the thrivikrama avathAram here, thiruppANAzhvAr has talked about how the indrAthi dEvas became servants (begging for His help), how brahma worshipped His feet and became a bhakthA (ArAthakan), and how rudrA obtained theertha prasAdam and became purified (bhoothan).

anRu - anRu is not the time when He (Rama) reached janasthAnam (which He reached after leaving dandakAraNya) where the Rishis asked for His help in defeating the asurAs. anRu refers to when He as the protector (rakshakan) looked at His subjects (rakshyavarkkam) - neeNmudiyan.

nErntha nisAsarar - Instead of singing pallANdu to His beauty, these asurAs that cannot even show their faces, are opposing Him. AzhvAr is disgusted with these asurAs who, when they had the opportunity to see Him in person, instead of praising Him (mangalasAsanam), chose to oppose and be crushed by Him. They are opposing Him like small insects attacking a fire.

kavarntha - Start with modesty and yet when they reach the target they fall upon them like hounds. After defeating mArica and subAhu, Rama did not face any battle. So, when these asurAs opposed Him, His arrows went after them like a snake after its prey.

venkaNai - His arrows are like Him; when launched they leave like an arrow; when they reach the target they are like fire (kAlAgni).

kAkuththan - Born in the kAkuthsa vamsam.

uvanthvuLLathanAy ulakamaLanthu aNdamuRa nivarntha neeNmudiyan - talks about his seela guNam.
anRu nErntha nisAsararaik kavarntha venkaNaik kAkuththan - refers to his veera guNam.

AzhvAr started with His feet (ulakanamaLanthu) - vikramam, and ended at His divine shoulders ("kavarntha venkaNaik kAkuththan") - parAkramam.

kadiyAr pozhil arangathammAn - Tired from having measured the worlds and defeating the asurAs at janasthAnam, He came and rested His feet and His shoulders at Arangam of the fragrant forests.

arangathammAn - To save everyone who could not be there when He was Rama, He is now resting at Srirangam.

araissivanthavAdaiyinmEl senRathAm - Like the mind of an hungry man going after food, so does AzhvAr's mind go after His thiruppeethAmbaram.

enasinthanai - AzhvAr spoke of thought ("sinthanai") to stress the importance of our thoughts always being on emperumAn. AzvAr says his thoughts that for so long chased after small matters and got caught up in them (their dress), having reached His feet are now forever caught in His dress.

First Song: kamalpAtham vanthu - sAthanAbhAvam
Second Song: senRathAM - athikAriswaroopam

First Song: neeNmathiLarangam - rakshagathvam
Second Song: kadiyAr pozhilarangam - bhOkyathvam

First Song: nimalan ninmalan - He helps us without expecting anything in return and He considers it His profit when He attains us. AzhvAr wondered if it was possible to reach such a being.
Second Song: AzhvAr has found that it is possible to reach Him.