"For her or against her?"
Translation:Für sie oder gegen sie?
No, "ihre" means "her" as in "her house", "her friend", "her dress" (i.e. possessive adjective). "Sie" here means "her" as in "I see her", "I hear her", "for her", "without her" (i.e. direct object pronoun). You would be able to use "ihr(e)" if the sentence was something like "for her school" or similar.
A simple test: what would the masculine version of the sentence be?
It's not "for his" but instead "for him" -- so "her" here is the personal pronoun, not the possessive.
Isn't the verb supposed to be in the second position? Or is that only when their is an direct object?
für and gegen require the accusative case -- sie is the accusative case while ihr is the dative case.
(In English, accusative and dative got merged into a single objective case, which looks like the old dative for some pronouns, e.g. "him, her, whom" look like German dative ihm, ihr, wem in their endings. German still keeps them separate.)