Google Nest Community

So hook them up to your nest according to color. W(hite), R(ed), Y(ellow), G(reen), and put the blue on the C terminal.

Are there any other wires in the bundle in the wall?

I'm assuming you're taking a gas furnace. What were need to do is locate your furnace and open on panel where the thermostat where's connect. We need to see what wires are landed on the control board.

What type of heating system do you have?

In order to determine what wires are what you'll need to go to the furnace and open the door to see what wires are landed where. They should be the same on both ends. I'm an HVAC professional. Any other help needed just ask.