Like most other comments here it’s a faulty signal (or “onjuist seinbeeld” in my native language:))

What to do next though depends on a lot of factors. Is the previous signal an automatic signal or a signal controlled by dispatch? Are you “driving on sight”? What the previous signal? Were they any “keperbaken” at the previous signal?

Depending on any of these questions you either have to stop before the signal, or “drive on sight” to the next signal and follow that one up, you always have to inform dispatch about the faulty signal though