I have a Keeprite SP 80 High Efficiency model # NUG5075BFB2 the pilot is lit but the furnace won't fire the thermostat( new batteries) is set for 70. The filter is clean, I tried turning everything off including the gas and the thermostat then turned everything back on the pilot is on but the furnace won't fire. Any suggestions

Make sure the power is turned on at the furnace and in the main house electrical panel. If so then test for 24 volts at the transformer.

The blower fan has power but I'm not sure what or where the transformer is or what it looks like

I feel you might be in overhead especially since you have no idea what a transformer is making your effort to repair your furnace rather futile along with the fact that you could be hurt in the process. I recommend you call a proofessional for on site service and repair.