A white eyebrow appeared in my left eye and it never stops growing

What do you mean 'appeared in your left eye'. Do you mean a white hair appeared in your left eyebrow. If so, cut it off.

Yes I cut it off but it grows again and again

Try plucking it out then but why does it matter ?

I am just asking if it is a big problem or it will disappear soon.

You will just have to keep plucking it.