We need more context. A "grill" is a kind of cooking stove in which things are cooked on an open metal frame or grid over a fire. In a restaurant, a "grill" can mean hot, flat metal plate, heated to a high temperature in any way, on which food is placed directly. By extension, a "grill" is a name for a style of restaurant... or the place in a "bar and grill" where meals are cooked. I don't know how Belgian or French pommes frites are really cooked, but in the U.S. "french fries" are usually made by deep-fat frying; cut sticks of potato are put in a metal basket and lowered into a bath of hot oil. It is possible that "french fries at the grill" could mean that the cut sticks are fried on a grill instead of dipped into hot oil. On the other hand, it someone said "I'm going to get french fries at the grill" it might just mean something like this: we're at a ski slope, and there's a cafeteria-style restaurant; Jessica is going to get cocoa here, Fred is going to get chili over there, and I am going to get french fries at the grill.

"French Fries at the Grill"? I don't know what that is... Normally French Fries are... Fried! lol, not grilled, maybe it is a special recipe?

French fries can also be baked, see for instance: http://culinotests.fr/news/les-frites-au-four-de-nellou Maybe that's what it means?