Is again a pronoun

No, the Word 'again' is an adverb, a Word that modifies a verb, an adjective, or another adverb.

Examples:

I hit that mailbox again. (hit again, modifies the verb 'hit')

I sat and admired the again orderly room. (modifies the adjective 'orderly')

We are again out of money. (modifies the adverb 'out')

A pronoun is a Word that takes the place of a noun in a sentence.

Example: We are again out of money. It never lasts to the end of the month.

The pronoun 'it' takes the place of the noun 'money' as the subject of the second sentence.