Cut through the bullshit essentially means be honest and get to the point. E.g. If somebody wanted to break important news to their family and friends and starting giving a long-winded backstory, his family members might get impatient and say "Cut through the bullshit and just tell us!". Similar sayings: Cut the crap Cut to the chase Stop beating around the bush

"Bull" is a politely-shortened form of "bullshit" (ie. lies and nonsense).

@Alan, I wouldn't use it either :) Thank for the explanation

In addition, if you think someone is lying to you, you can, in an informal context, say "Bull." Or "BS" or "bull shit." Or: "That sounds like bull (or BS)." Or, to be a little ruder, "That sounds like bull shit." All these terms are considered (more or less) vulgar, so I wouldn't use them around people I was trying to impress, such as my boss--and probably not my parents.

Yes, this is what I understand from the context but not from words. Thank you for dropping a comment :)