Dal segno means 'from sign' and is usually abbreviated as D.S. near the end of a tune. It should be interpreted as an instruction to repeat the sequence just played from the occurrence of a segno marker to the end. A dal-segno-construction is often enhanced with a few extras:
Dal Segno al fine: repeat from segno to the marker fine and stop there.
Dal segno al fine et poi la Coda: repeat from segno to the marker fine (if any) then plat the coda (tail)
So everything up to the coda-sign is played first, then everything between the segno and the fine, and lastly everything after the DS or from the Coda-sign.
It is possible to mix dal segno and other repeat constructions (prima volta/secunda volta).
A simple form of the dal segno construction is a da capo.