What texture makes up a character in a video game

There is no 1 answer to that question.

A texture is just a term for am image that is wrapped around a 3d model in a game to make it look like a real person or item.

Even walls in video games are only flat surfaces with a texture applied to them. Think of it like wallpaper.

In a 3d video game, the world and characters are made up of flat surfaces, called polygons, which are basically just triangles. Without textures over then all you would see is a wireframe graphic, which wouldn't be very playable or immersive

Different textures can be applied to the same 3d model to make up that seem to be different characters. They will have the same shape but are painted differently.