Instantaneous velocity equal instantaneous speed plus direction?

When the length of the time is decreased more and more ,average velocity of the particles equals instantaneous velocity.

It is the speed or velocity at a particular instant.

At a small time interval, the average velocity is approximately equal to the instantaneous velocity. However, the values of the average velocity and the instantaneous velocity approach each other ,...

In uniform motion.

When an object is in constant motion (when there is no acceleration). At any point in that motion the average and instantaneous velocities will be the same.