There are power-ups that can be won during the ascent of the Alpe, at three set points. You only get the chance to win them if you’ve done two prior ascents of the Alpe in the last 30 days (at least that’s how it used to work; it might have changed).
Based on your best times to the set points up the Alpe, Zwift gives you a ‘carrot’ to chase, with a countdown to help you see how long you have left to get to those points. In your case above, you’d get the van power-up if you got to the target point in less than 28 seconds.
Check out the meandering discussion below, for some more details and illustrations: