This diagram shows two switches in the same box with two separate 120 volt sources. Three-wire cable is supplying the source for both switches with the black and red wires going to the bottom switch terminals. The black wire from each light is connected to the top terminal of their respective switch. The white and ground wires are spliced to run to each light fixture.
The hot wire to the fan in a fan/light kit will usually be black and the light wire will be blue. The white wire is usually the neutral which is always connected directly to the source neutral, either at the source or through a splice in the switch box. The white wire may also be used to carry current when necessary.
This page contains wiring diagrams for two outlets in one box. Included are arrangements for 2 receptacles in one box, a switch and receptacle outlet in one box, and 2 switches in the same box. In this diagram, two duplex receptacle outlets are wired using pigtails spliced to connect the terminals of each to the source wires.
In this diagram, a light switch and receptacle are wired in the same box. Both devices are spliced to the same hot source and the neutral to the neutral on the receptacle, and through to the light fixture located in a separate box.