Local route at the junction

This sign means: At the junction. It is a direction sign on a non-primary or local route, where signs have black borders. It gives route information, not an order.

Official Highway Code caption: “At the junction.”

Listed under “Signs on non-primary and local routes – black borders” in The Highway Code: traffic signs (GOV.UK). For every sign in more detail, see the Department for Transport’s Know your traffic signs.