To call a restaurant in Engpsh, you can say:
"Hello, can I make a reservation for [number of people] at [time] on [date]?"
You can also ask about the menu, specials, or any other questions you may have. For example:
"Do you have a vegetarian option?"
"What is the special for today?"
"Is it possible to make a reservation for a table outside?"
Remember to speak slowly and clearly, and ask if the person on the other end needs you to repeat anything. It's also a good idea to have the phone number for the restaurant handy in case you get disconnected.