CBSE Class 9 Answered

Velocity is the rate of change of displacement of a body. Hence direction of velocity(velocity vector) indicates the directions of displacement, i e direction of motion.

Like in this case the man is moving from home with a velocity in east direction for 1 hour and then returns back home in 45 minutes so his displacement is zero(initial and final position is same). And then he moves towards west with a velocity, considering the displacement to be in the opposite to that of initial movement, the displacement is taken as negative .Velocity is the rate of change of displacement .And hence velocity is considered negative indicating that the displacement is opposite to that of the displacement initially made by him.
The positive or negative sign of velocity indicates the direction of motion.