This is a light fixture that is normally attached to a wall, to provide subdued, upward lighting. (The concept originated with torches many hundreds of years ago.)
Around the swimming pool, sconces can be especially attractive and effective around a cabana or pergola. A series of small, low-profile sconces can also do an excellent job of lighting stair steps or other walkways at night.
Note: Some people refer to decorative scuppers (such as a lions head scupper) as a sconce. This is technically incorrect.