"Mohamed's restaurant is pretty and expensive."
Translation:مَطْعَم مُحَمَّد جَميل وَغالي.
In Arabic, in order to translate "the X of Y" or "Y's X", we use a genitive construction:
(EN) Y's + X -> (AR) X (without definite article) + Y (with definite article, or a proper noun)
(EN) Mohamed's restaurant -> (AR) مَطْعَم (without definite article) + مُحَمَّد (a proper noun)