Yarım is uses for objects. Buçuk is uses for times. But both of them means 'half' For ex; Yarım ekmek. - Half bread. Bir buçuk saat. - One and half hour. Yarım patates. - Half potatoes. İki buçuk ay. - Two and half months But if the time is shorter than 1, you must use 'yarım'. For ex; Yarım gün. - Half day. Yarım yıl. - Half year. I hope it will be help you :)