25 forms means maximum I can create per month or I can get 25 Sign Ups for our event?

The forms limit does not reset monthly, but it means the number of active forms you can have in your account, for example, you could have 100 forms, but only 25 will be active, the rest will be disabled. 

The same happens if you have already reached the limit and you want to create more forms, you will need to disable those un-used forms in order to create new ones.