Learn Turkish: Fırın çok sıcak, et yanar. - The oven is very hot, the meat burns.

The suffix -ar is the aorist (simple present) tense. While yanıyor would mean the meat is burning right at this exact moment, yanar expresses a general truth, an inevitable result, or a warning: 'when the oven is this hot, meat burns.'

How is the aorist formed for the verb yanmak in this sentence?

The root is yan- (to burn). Because it is a single syllable ending in a consonant, it takes the -Ar form of the aorist suffix. Following a-type vowel harmony (the 'a' in yan- is a back vowel), it becomes -ar, giving us yanar.

I learned that fırın means 'bakery'. Does it also mean 'oven'?

Yes! Fırın can mean both 'bakery' and 'oven'. You can usually tell which one it is from the context. Since the sentence talks about it being very hot (çok sıcak) and cooking meat (et), 'oven' is the most natural translation here.

Could I use yanar to say 'I burn the meat'?

No, the verb yanmak only means 'to burn' when the subject itself is burning, being destroyed by heat, or catching fire (like the meat in this sentence). If you want to say that you are burning something, you have to use a different verb: yakmak.