This sign is called a Repeat sign.
When playing sheet music, this sign would mean to repeat all or some of the previous notes.
An accent sign would be a ">" above a note. A final barline would be this sign but without the two dots. A double barline would be a "||" in the middle of a sheet music.
Let me know if you need any clarifications, thanks!
(Source: I play the piano/drums/violin and studied music theory)