Pronominal - means playing the part of or relating, to a pronoun.
Pronoun - A pronoun is simply a word used instead of a noun. Here are some examples of pronouns ; I, me, you, he, she, it, that, they, each, who, somebody.
Pronominal possessives - These include my, your, our, their, his, her and it's. They differ from other pronouns as they refer to a noun and show possession.
They help to modify that noun and are technically adjectives.
His muffins are burnt but hers are perfect.
The pronominal possessives in this sentence are His and Hers they are used to refer to muffins.