I have a 2001 yukon denali and im getting these trouble codes(p0171bx2, p0102b, p0174b) and i dont know where to find out what they are. Also it read im lean in bank 1 & 2

Po 0102 is mas air flow sensor maf/vaf
p0171 bank 1 too lean
p0174b bank 2 too lean
What you have here is either a defective mass air flow sensor and or a possible broken loose or rotted vacuumn line or hose creating this havov, with the engine warm and idling in Park tap the air flow sensor in its housing and see if the engine gets upset(rough) if so replace the sensor its expensive.
If ok have the vac system checked for possible leaks in the hoses at around the intake manifold gasket area etc, fix and replace as needed.