What’s the meaning of this motorway sign?

Explanation: When the red lights are flashing, don't go beyond this signal. This sign shows that all lanes ahead are closed and you mustn't enter the motorway. Motorway signals are located on the central reservation, to the left of the hard shoulder, on overhead gantries and at the entrance to the motorway.

Category: Traffic Signs (2021)

References: Know Your Traffic Signs: Page 91