Learn Turkish: Ablamın kuaföre gitmesi lazım. - My sister needs to go to the hairdresser.

To say someone needs to do something, Turkish uses a structure that literally translates to "someone's doing [action] is necessary." Because the action belongs to your sister, you use the genitive case. Ablam becomes ablamın ("my sister's") to link with gitmesi ("her going").

How exactly does gitmesi mean "to go" in this sentence?

It literally means "her going." We take the root verb git- (go), add -me to turn it into a noun (going), and then add the third-person possessive suffix -si (her). Together, ablamın ... gitmesi means "my sister's going."

Why is it kuaföre and not just kuaför?

The verb gitmek (to go) requires the dative case to show the destination or direction. Adding the -e suffix to kuaför turns it into kuaföre, which means "to the hairdresser."

Can I use gerek instead of lazım in this sentence?

Yes, absolutely! Ablamın kuaföre gitmesi gerek means exactly the same thing. Both words are used interchangeably with this verbal noun structure to mean "needs to" or "has to."