Formal:
* Sur la plage: This is the most literal and common translation.
* À la plage: This is another common option, meaning "at the beach".
Informal:
* A la plage: This is the most casual way to say "on the beach".
* Sur le sable: This literally means "on the sand" and is more specific.
Here are some examples:
* Je vais à la plage: I'm going to the beach.
* On peut se rencontrer sur la plage: We can meet on the beach.
* Il fait beau sur le sable aujourd'hui: The weather is nice on the sand today.
You can choose the best translation based on the situation and your personal preference.