You’re driving on a road with several lanes. What do these signs above the lanes mean?

On some busy roads, lane control signals are used to vary the number of lanes available to give priority to the main traffic flow. A green arrow indicates that the lane is available to traffic facing the signal. A white diagonal arrow means that the lane is closed ahead and traffic should move to the next lane on the left. A red cross means that the lane is closed to traffic facing the signal.