It is a possessive pronoun so it means "her" not "she". The endings are a matter of noun agreement, so it changes based on the gender and the case of the noun it precedes.
Nominative: Masculine: ihr; Neuter: ihr; Feminine: ihre; Plural: ihre
Accusative: Masculine: ihren; Neuter: ihr; Feminine: ihre; Plural: ihre
Dative: Masculine: ihrem; Neuter: ihrem; Feminine: ihrer; Plural: ihren
Genitive: Masculine: ihres; Neuter: ihres; Feminine: ihrer; Plural: ihrer
the possessive pronoun "ihr" can also apply to the 3rd person plural and mean "their." Context is needed to differentiate. The formal possessive pronoun is "Ihr" (capital).
I think you meant "her". It all depends on the word it's refering to.
Masculine and Neuter nouns take "ihr" and feminines and plural take "ihre".
Here it's refering to her brother, which is masculine therefore: ihr. But if was her sister instead, it would be: "ihre Schwester", because Schwester is a feminine noun. It all seems confusing at first, but eventually one gets the hang of it.