When you send an email that includes a Meeting Scheduler link, your recipient will be brought to a page where they can select a specific time to meet from all the times you have available (or offered in the case of Custom Availability). Only time slots that are still available (not busy) on your calendar will be displayed on that landing page.
Yesware's Meeting Scheduler feature checks your calendar for conflicts so that it will not show recipients a time that is now unavailable.