What must you do in this situation?

In the situation depicted, where there is a flagman directing traffic near a level crossing, the correct action is to stop in front of the level crossing. This is in accordance with German traffic rules, which prioritize safety at crossings where trains may pass.

The flagman is there to ensure that vehicles do not proceed when it is unsafe, as trains cannot stop quickly. Ignoring the flagman's signals or driving past them can lead to severe accidents. Always obey traffic control devices and signals in such scenarios to prevent collisions and ensure the safety of all road users.