What does DPS mean?

Solution 1:

DPS means, simply, Damage Per Second. It is a numerical value that represents the amount of damage one player can inflict onto another or the environment.

DPS is not dependent on class as much as it is loadout and abilities/skill - it can change drastically based on what weaponry you use.

It can be calculated by attacking a mob or similar non-stop for five seconds, and dividing the total HP lost by 5. Typically, the DPS stats you see in game are "optimal", meaning assuming you attack perfectly for one second.

Solution 2:

Yes it is an appropriate use of the term. It is more often used to refer specific damage output per second in the literal sense. But classes that are known for specifically dealing damage can be referred to as DPS. It can be used similarly to how a class would be known as a healer or tank class.

Most classes in most games deal damage and would have a DPS but as you used the term, most games have classes that are specifically used to deal significantly more damage than others. Those can be referred to as DPS classes in many circles.