FBD provides a visual for every force that the object experiences. It can tell you the direction by showing the direction and magnitude of the forces. You can calculate the net force, example being that the applied force is 300N and the force of friction is 100N, the net force is 200N in the direction of the applied force. (Fnet= Fa- Ff).
How do free-body force diagrams help you determine an object’s direction of motion?