Very often when you reach the end of a road you’ll be dealing with a Give Way junction (double dotted lines, and sometimes an upside down triangle), but sometimes you’ll need to deal with a Stop junction. The three things that make it different to a Give Way are that it has a thick solid white line, it says STOP on the floor, and it has an octagonal sign in the air, also saying STOP.
They are usually junctions where the visibility is poor, so you need to be extra careful. Legally, you must come to a complete stop when you are at the junction, and can see well to the left and right of the new road (as well as ahead). Even if it looks clear, make sure your wheels have completely stopped and check around again. Then, just as usual you can carry on when you know it’s safe all round.