In Diablo 3 for the PC, DPS is very important because it stands for how much damage you put out every second. The more damage you do per second, the faster mobs die.
Your DPS is shown in the character screen, though you may not have noticed it because it’s labeled as Damage right beneath your Armor.
It’s important to keep an eye on this stat, because due to the different factors of a weapon or item it may look like it will increase your DPS, but it may not once the calculations are made.