What does the staggered junction warning sign mean?
Staggered junction ahead, with side roads on each side that do not line up.

A red triangle with side roads joining from each side, offset.
What you must do
Slow down and watch both sides for emerging traffic.
Where you will see it
Where two side roads meet the main road close together but offset.
Test yourself
The theory test asks you to recognise signs like this one. Try the road and traffic signs quiz (with an easy and a hard set), or read the signs revision notes. Source: Know Your Traffic Signs.
Other common road signs
Meaning based on Know Your Traffic Signs and The Highway Code. The sign image is an official Department for Transport sign (Crown copyright) from Wikimedia Commons, reused under the Open Government Licence or the public domain. Always check the current Highway Code on gov.uk. Not affiliated with or endorsed by the DVSA.