• anantasya — of the unlimited
  Genitive of Ananta — Balarāma is Ananta-deva, the thousand-hooded serpent on whom Viṣṇu reclines. The epithet quietly identifies Saṅkarṣaṇa with His own bed: the support of the cosmos and the brother of Kṛṣṇa are one Person.
• māyā-martyasya — who appears as a mortal by His illusory potency
  Compound: māyā (illusory power) + martya (mortal). The classical Gauḍīya formula for the avatāra's appearance — Bhagavān seems martya only because His own yogamāyā lets Him. Realists can mistake Him for human; bhaktas see through māyā to the Person behind it.
• aprameyasya — of the immeasurable
  From a (not) + pra + √mā, 'unable to be measured.' Balarāma cannot be weighed by intellect, ritual or category. The verse pre-empts the reader's temptation to summarize what they have just read — 'these are only some of His līlās.'
• bala-śālinaḥ — of the mighty
  Compound: bala (strength) + śālin (possessing). A play on His name — Balarāma is bala-śālī because bala is in His very name. Gauḍīyas note that His name means both 'He whose strength gives delight' and 'the personification of bala' — He is strength taking pleasure in itself.

The chapter pauses to breathe: 'there are countless such pastimes of Balarāma, the unlimited, the immeasurable, who by Māyā appears to be a mortal.' Everything just told is a single bead drawn from an endless string. The Saṅkarṣaṇa who supports infinite universes contracts His infinity into a Yadu prince — but the contraction is a courtesy, not a diminution; the chapter we just read is a sliver of His unbounded conduct.