hers

As a noun taxonomy

is the science or the technique used to make a classification.

As a pronoun hers is

that which belongs to her; the possessive case of she, used without a following noun.

As pronouns the difference between theirs and hers

is that theirs is that which belongs to them; the possessive case of they, used without a following noun while hers is that which belongs to her; the possessive case of she, used without a following noun.

Hers is a synonym of eirs.

As pronouns the difference between hers and eirs

is that hers is that which belongs to her; the possessive case of she, used without a following noun while eirs is (neologism) that which belongs to em, theirs (singular).