Learn Turkish: Galiba kahraman kazanmış.

The suffix -mış is the inferential past tense. You use it when you did not see the action happen yourself, or when you are deducing it. Because the speaker says galiba (I guess), they are guessing the hero won rather than stating a fact they witnessed, so -mış is the perfect fit here.

Does the word galiba always require the verb to take the -mış ending?

Not always, but they are a very natural pair! Galiba means 'I guess' or 'probably.' Since it shows uncertainty, it pairs perfectly with the -mış tense, which also shows you are not 100 percent sure. You can use other tenses with it depending on what you are trying to say, but they go together extremely well.

Where is the personal suffix on the verb kazanmış?

The subject is kahraman (the hero), which is a third-person singular subject (like he, she, or it). In Turkish, third-person singular verbs do not take an extra personal suffix. The base verb kazanmak (to win) just takes the tense suffix -mış and stops there.

Does kahraman refer only to male heroes?

No, Turkish does not have grammatical gender. Kahraman can refer to a male hero, a female hero, or simply the main character (protagonist) of a story.