When you click the Edit button in the close votes review queue, it knocks the post out of the queue, so other reviewers will not see it and it will probably not get closed. This is very bad if the post is one that should be closed.
If you want to vote to Leave Open, do so - it takes three Leave Open votes to remove a post from the queue - the Edit button is a hammer and should only be used if you are absolutely sure your edit to the question justifies keeping it open.
If you want to edit to make corrections anyway, that's great; just click the link button to the right of the post, then edit (or suggest an edit) as normal. If you want to edit the post and you think the post should be left open but you are not sure enough to hammer it out of the queue (I am often in this situation) then do as above, return to the queue and click Leave Open.
If you accidentally Edit a post from the queue that you think should be closed, then find the post and cast a close vote to put it back in the queue, or come into chat so someone else can take a look.