An SMBL file is a game data file used by Super Meat Boy, a video game about a red, cube-shaped character called "Meat Boy." It stores information about a playable level, which includes the palette that makes up the background, tiles included in layers the character can interact with, and usable objects and props.

You most likely will only encounter an SMBL file if you play Super Meat Boy in Windows and are navigating the data files in the game installation directory. The files are typically not opened by gamers since they are referenced by the game to load information about playable levels in the game. However, gamers may also create, open, and modify SMBL files using the Level Editor included with the Steam version of Super Meat Boy. SMBL files are located in the following directory in Windows: C:\Program Files (x86)\Steam\steamapps\common\Super Meat Boy\levels