DPS

stands for Damage Per Second, and denotes the amount of damage dealt by a weapon or Ability over the course of one second. Generally, the higher your the better, as it means you're doing more damage.
 should account for the shot damage, shots per second, and reload period for weapons, or damage and cooldown period for Abilities. Chainguns, for example, are considered to have a much higher than Launchers because of their large magazine size and faster reloading time.
That said, a low isn't necessarily a bad thing. Your weapon could take a long time to reload but have high enough damage to kill the target in one shot, making reload time irrelevant. In high level instances when in squad it may be useful to use rapid firing sonic Chaingun with low DPS for single enemy Crowd Control. For multiple enemies you can use sonic Grenade Launcher. Due to low DPS you won't be aggroing enemies. Rapid fire of Chainguns will have higher chance to knockback enemies with sonic critical hits. AoE nature of Grenade Launcher has good chance of knocking down multiple enemies at once.
See: Wikipedia:Damage per second for more information.
Category:Terminology