Why does my light fixture have 3 wires?

The simple explanation is that a 2-wire system does not include a Neutral wire at the light switch, the 3-wire system does include the Neutral at the switch.

What are the 3 wires coming out of ceiling?

Black wire is for the fan.Blue wire is for the light, if light is included with the fan.White wire is neutral.Green wire is for the ground.Red wire is sometimes included and acts as a conductor to carry power to the light kit.

How do I wire up a ceiling light?

1:259:07How to wire a ceiling rose - lighting circuits explained - YouTubeYouTube

Can you connect 2 wires to 3?

You can retrofit your 2-wire outlets with new 3-wire or GFCI receptacles in the same outlet box without any rewiring.