What is the meaning of يا?

O; hey; you; vocative particle preceding a noun used in direct address, only rarely omitted in such contexts

vocative particle

either ... or

or

O!

vocative particle

either ... or

Hey

already

either...or

vocative particle

accusative particle, used with pronominal suffixes to express English object pronouns, like me, him, etc.

vocative particle

either ... or

Alternative spelling of ايا (iyya-), especially after a vowel

Source: wiktionary.org