This important, and very common, sign tells you to repeat a section of music.
Two dots in the five lines of the stave mark the beginning and the end of the section that is repeated. When you get to the sign on the right, you go back to the opening set of dots and sing that section again.
Help! I can’t find the opening dots.
If you get to an end-repeat sign and you can’t find the begin-repeat sign, that means repeat from the beginning.
If there are two lines of lyrics underneath the music, sing the second ones the second time through.