Electric current flows from a higher potential to lower potential. When a circuit is connected using conductors, an electric field is established in the direction towards lower a potential point from a higher potential point. The electric field exerts an electric field on the electrons in the conductor in the opposite direction. So electrons drift in the opposite direction from - to + terminal. We call direction of current to be opposite to the direction of motion of electrons.
Also, like water or stones etc. move from a higher energy point to a lower energy point, current flows from a higher energy point or higher potential (+terminal) to a lower energy point or potential (- terminal).