If it is a EVAP charcoal canister, then yeah, it absorbs fuel vapors so they don't vent into the atmosphere. Most modern vehicles have them as emissions controls. Unless the system is not functioning (easy to clog if you overfill the fuel tank), they don't tend to be a determent to performance and are often worth leaving in place just so if you park in a garage it doesn't fill the space with the smell of gasoline.