What model heatpump do you have? Is it a Rheem/Ruud, or something else? This will determine the thermostat connections and setup.

Rheem

You need to post the model number of the thermostat to verify if it can support your equipment.

OK, Rheem and Ruud use the "B" terminal for the reversing valve (all the others use "O" - for "others"!)

So connect the the reversing valve wire to the O/B terminal and in the thermostat setup routing, select "B".

You need to trace all the wires back from the condenser to the heat exchanger and to the thermostat to know how the colors are connected. Here's how they are typically labelled:

R red - Power

G green = Fan

O orange ???

B blue - reversing valve (heat)

W2 white - aux heat

Y yellow - compressor (cool/heat)

E black - emergency heat

On the new thermostat, L is usually error notification and C is usually common. They don’t appear to be used on your existing system with the old thermostat (unless it’s that odd “O” wire)..