What are the negative numbers to my tags? They don't correspond to my reputation or votes?
Sorry if its somewhere explained already.
That would be the total upvote(+1)/downvote(-1) score on questions or answers with that tag. The $\times$ number following it counts the number of questions or answers. Upvotes on answers count +10 reputation, and downvotes on answers count -2 reputation. Upvotes on questions count +5 reputation, and downvotes on questions count -1 reputation.