I gave a edit suggestion and when it was approved I saw that only one person has approved it and that is the question owner with 16 reputation. How? Please explain me.
From How do suggested edits work? on Meta Stack Exchange:
Who can vote on a suggested edit?
- The owner of a post may cast a binding vote to accept or reject any modification of their post.
- All users with the edit privilege may vote on suggested edits to posts.
In other words, you only need 2000 reputation if you aren't the owner of the post. The question owner can approve or reject any suggested edit to their post regardless of their reputation level.
This is intentional, not a bug.