When is a body said to have:
Uniform velocity
Variable velocity

Hint: Recall what is velocity. Understand the meaning of terms uniform and variable. After form the meaning with the help of examples for the terms uniform velocity and variable velocity.

Complete step by step answer:
Velocity is defined as the rate of distance/displacement covered by an object in motion.
Uniform means unchanged or remaining the same.
So, when displacement or distance changes constantly with respect to change in time at equal intervals then velocity remains unchanged. This is known as uniform velocity. When a car is moving on a straight line without changing its speed, then we say it is moving with uniform velocity.

Variable means that keeps on changing.
So, when distance changes unequally with respect to change in time at equal intervals then velocity keeps on changing. This is known as variable velocity or non-uniform velocity. When a car changes its path then its velocity changes.

Additional Information:
There are two types of quantities, vector and scalar. Scalar quantities are those which have only magnitude. While vector quantities have both direction and magnitude.
Distance is a scalar quantity while displacement is a vector quantity. Similarly in case of speed and velocity, velocity is a vector quantity while speed is a scalar quantity.

Note: Uniform motion and uniform velocity are the same. Also, Non-uniform motion and variable velocities are the same. Do not get confused between terms. It is very important to understand the meaning, and hence the definition of all the terms used to get clear and better understanding.