What is the name given to a word instead of a noun?

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

A pronoun functions as a noun in a sentence as the subject of a sentence or a clause, and as the objectof a verb or a preposition.

Examples:

The children visited their Aunt Jane.

She baked cookies for the children. (subject of the sentence)

The cookies that she baked were for the children. (subject of the relative clause)

Aunt Jane baked them for the children. (direct object of the verb 'baked')

Aunt Jane baked cookies for them. (object of the preposition 'for')