Learn Turkish: Toplantı için hazırlanmaya mecbur. - He is obliged to prepare for the meeting.

This is the focus of your current lesson! The adjective mecbur (obliged) requires the action you are obliged to do to be in the dative case (the "to/towards" direction). To add a case ending to a verb, we drop the -k to make the verbal noun hazırlanma, add the buffer letter y, and finally add the dative suffix -a.

Wait, isn't "to prepare" hazırlamak? Why is there an "n" in hazırlanmaya?

Yes, hazırlamak means to prepare something else (like a meal or a report). Adding the -n makes the verb reflexive: hazırlanmak means to prepare oneself or to get ready. Since he is getting himself ready for the meeting, we use this reflexive version.

Why doesn't toplantı have an ending before için? I thought için required the genitive case.

The postposition için (for) only forces the previous word into the genitive case if that word is a pronoun (like benim için - for me, or bunun için - for this). With regular nouns like toplantı (meeting), you just use the plain dictionary form of the word.

Where is the "he is" part of the sentence? There's no verb at the end.