Is trouble a pronoun

No, it's a noun (trouble, troubles) and a verb (trouble, troubles, troubling, troubled).

Pronouns are Words that take the place of a noun or a noun phrase.

Subject pronouns are: I, you, he, she, it, they, we.

Object pronouns are me, you, him, her, it, us, them.

See the following examples:

I am fine, you shouldn't trouble yourself.

The pronoun 'I' takes the place of the name of the one speaking; the pronouns 'you' and 'yourself' take the place of the noun for the one spoken to. The verb is 'shouldn't trouble'.

John and Jane are coming for the weekend. They won't be any trouble.

The pronoun 'they' takes the place of the nouns 'John' and 'Jane'. The noun 'trouble' is the object of the verb 'be'.