Question

If the displacement of a particle is equal to zero, then it's distance

Answer 1

If a body starts from some point, say A, goes in a circle and comes back to point A, then the displacement as defined will be zero. Because the initial and final points will be same and there will be zero distance between them. But in the same case distance will not be zero and will be given by the length of actual path traveled by body.
Hence, displacement can be zero, even if distance covered is non-zero.

Answer 2

$\huge\mathfrak{Heya}$

$\mathsf{There \ can \ be \ many \ situations.}$

$\mathsf{1st \ Situation \ :-}$
$<b>$
If the displacement of a particle is 0, then it can be possible that the particle does not cover any distance and the particle is at rest.

In this situation,

Displacement = Distance = 0.

$\mathsf{2nd \ Situation \ :-}$
$<b>$
It can be possible that the particle covers the distance but its displacement is 0.
This situation can be possible when a particle moves around a circular path and comes back to its starting point.

Here,
Displacement = 0
Distance = 2πr, where r = radius of the circle.
{Refer to the 1st image.}

$\mathsf{3rd \ situation \ :-}$
$<b>$
If an object is moving along a straight path, then it can be possible that displacement is equal to 0.
This situation happens when a particle covers some distance linearly and comes back to its original position.

Here,
Displacement = 0
Distance = x + x = 2x, where x = distance covered by a particle in one direction.
{Refer to the 2nd image}

$\huge\mathbb{Hope \ this \ helps.}$