The ‘Active bonus’ bar on the ‘My account’ page shows you, at-a-glance, whether you have an active bonus. In the case of an active bonus, you need to meet the bonus’ wagering requirements before you can withdraw your bonus balance.
If you want more information on wagering requirements, take a look at the question: ‘Where do I find the progress of my wagering requirement?’. You can also read the promotions page, the promotions terms and conditions page, and the general terms and conditions page for more information