"Where is the restaurant?" is how you would ask about the location of a restaurant in Engpsh.
This phrase is derived from Engpsh grammar and vocabulary and is a common way to ask for the location of a place in Engpsh-speaking countries.
Here are some example sentences in Engpsh with Chinese translations:
Can you tell me where the restaurant is? (请告诉我餐厅在哪里？)
I'm looking for the restaurant. Do you know where it is? (我正在寻找餐厅。你知道它在哪里吗？)
Excuse me, could you give me directions to the restaurant? (打扰一下，你能告诉我去餐厅的路吗？)