What do these traffic signs indicate?

This traffic sign combination is used in Germany to warn drivers about a level crossing ahead, but not directly on the road they are currently on. The triangular sign with the train picture indicates there is a railway crossing, and the additional rectangular sign with the arrow shows the location of this crossing relative to your route—in this case, on a road turning right.

The rule here is that you should be alert for trains when you turn onto the road indicated by the arrow because a level crossing is present there. This sign helps drivers anticipate the railway crossing before they actually get to it, allowing them to slow down and prepare to stop if necessary.

The other options are incorrect because this sign does not show the exact direction a train might come from (that's a different sign) nor does it indicate a diversion to avoid the crossing. It simply warns of a crossing located on the road in the direction of the arrow.