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.
A simple form of the dal segno construction is a da capo.