what that number indicated right to the username indicate?????

It's point. :)

indicat the number of the posts

Its the number of the posts to which u've responded yet and sometimes when u write a new discussion and before writing urs tags, if someone responses to urs that post then urs ranking is increased by a number. Sometimes, some problem takes place in the system of mylot and they cann't update our ranking quickly. I've suffered from this problem many times. This number is called "Ranking".

discussions youve responded and has responded to you