Here you have a couple of videos about Post-Processing for CFD and CFD analysis, are very good videos for introduction and also this fields are mentioned on them:
INTRODUCTION TO POST-PROCESSING by @psosnowski
ONLINE POST-PROCESSING WITH SIMSCALE by @psosnowski
CFD WORKSHOP (Turbulence explanation) by @Milad_Mafi
But in general P stands for Pressure of the fluid, U for the velocity of the fluid, k for the turbulence, Omega for turbulence dissipation rate.
Hope this helps you, I encourage you to follow the recorded webinars and workshops from Simscale Youtube Channel so you can get more expertise in CFD (I’m neither a CFD expert but I’m trying to )