Variance & Std Dev

Could someone give me the basics on reviewing one’s variance/std deviation statistics in order to improve your game?

Which (if any) are important to look at? Variance per session, per hand, per starting hand (eg AKo has a mean of .025 BB per hand with a std dev of .01) What do they tell you about your play?

Which of these stats (if any) can you get these stats directly from Poker Tracker?

Thanks.

SP