There's a map key on the right upper part of the map:

Red: Government & pro-government forces: Assad, Russia, Iran

Green: Rebels: FSA, moderate rebels(many groups: Ahrar Al Sham, Jaish al Islam etc), more radical groups like Hayat Tahrir Al-Sham HTS(ex Al-Nusra)

Black: Islamic State

Yellow: Kurds: YPG, PKK, Peshmerga, other

Blue: Golan Heights - controlled by Israel

Darker green: FSA groups and Turkish troops in Northern Syria