As in the picture, below, Beside the word "review", I can see the number "4".
but when i click on the word/num there is nothing to review, and still, the number "4" persists.
As already explained here on the general stackexchange meta, the review counter is the global count of review tasks for the complete community, not your personal count. It also includes the number of review tasks you have already handled (or can't handle) but which are still in the review queue for others.
This behavior is constant throughout the stackexchange network, so whether or not this is a good design is a topic for the general Stackexchange meta, not the specialized Politics.SE meta.