Note: This functionality will only be available for you if you've also added the Planning Booster to your licence.

In the calendar's week view you'll see a bar below each day of the week. This shows your total availability for that day, based on the amount of hours per week you have set. The bar will fill up based on the tasks, meetings and calls you have planned in your agenda for that day. 

When the bar is green, it means everything's okay and you have some room left in your schedule to plan more work. Orange means you're already overbooked for that day in particular. If you hover over the bar, you'll see the amount of hours/minutes you're overbooked.

Planning

The availability bars also take all planned tasks, meetings and calls from your planning into account. So even if a task is not exactly scheduled in your calendar, but it is due on that day and planned via the planning, your availability decreases.