The western terminus of the highway is at an intersection with SR 49 in the unincorporated community of Reeltown.

The eastern terminus of the highway is at an intersection with SR 14 west of Notasulga.

SR 120 is just over 4 miles (6.4 km) long.

It travels generally to the southeast and is routed along a two-lane road.

The entire route is in Tallapoosa County.