L1-5 is the ground combo for every fighter (includes multi-hit combos like Filia and Big Band) - can also be written as G1-5
J3 is the air/juggle combo for every fighter (again includes multi-hit combos like Painwheel and Squigly)
D1-2 is the dash combo for every fighter (again includes multi-hit combos like Ms. Fortune and Robo Fortune)
So the combo D1-L5-J3 means you use the first hit of the dash combo, all hits for the ground combo, swipe up and tap to activate air juggle, then all hits for the air juggle.
Hopefully this helps some!