Dear Student,
Let an object be moving in a circular path.
After completing one revolution, distance travelled by the object will be equal to the circumference of the circle,
that is, 2πR ( for a circle of Radius R)
But, since the initial and final position of the object is the same, the Displacement covered by it is equal to Zero.
So in this case, the object has covered some distance but it's displacement is still zero.
Regards