Replacing double light switch 4 black and one red
It looks like you have something like this.

The top switch is the three way and controls the light along with the other dimmer switch. The bottom one is is a single pole that controls a light by itself. You're going to want to buy a switch just like this and wire back the same. As long as you make sure the wires go back in the same positions, you'll be fine.
As someone mentioned, putting some tape around the wires as they are pulled off might help to identify them later. You can get different colors of electrical tape at a hardware store. Also important is to make sure the power is turned off to that switch before working on it to avoid being shocked.
When in doubt, call a professional.