Whenever you need to edit a form or a view you will need to check it out.  The reason being, is because you don't want to have two people editing the same view or form at the same time and then there be inconsistencies inbetween the forms or views.  

Once you are finished editing the form or view, you can either check in the form or view to upload the changes you have made, or cancel checking out the form or view to revert back to the previous state of the form or view.