IMDB records this movie's genres as "Action,Comedy,Thriller". It's rated R due to (according to the MPAA) " strong violence and language throughout". Salma Hayek is in it, and if you want to hear Salma talk dirty, this is your go-to flick.
Ryan Reynolds plays a private bodyguard specializing in escorting threatened individuals to safer places. He's at the top of that game… until he isn't, as a crooked Japanese businessman is picked off by a sniper shooting through the window of a private jet.
After some time passes, Ryan is still in the dumps about that, but he gets a shot at redemption when his ex-girlfriend recruits him to escort Samuel L. Jackson (the titular hitman) from London to the Hague, where he is to bear witness against murderous dictator Gary Oldman. And of course, Gary has a veritable army of mercenary thugs to deploy against Ryan and Sam. And there's an Interpol mole (Joaquim de Almeida, who might as well be wearing a "MOLE" sign taped to his back).
There is a lot of impressive, inventive, action and violence that must have cost a lot of money to film. Also a lot of wisecracking, profane, banter between Ryan and Sam. Gary Oldman is the only cast member who can be accused of acting.
Apparently it was successful enough to spawn a sequel, out later this year, The Hitman's Wife's Bodyguard, with Ryan, Sam, and Salma returning.