The main message here seems to be "trouble could be lurking under your very nose" -- Russian spies could be anywhere, and there's nothing you can do about it unless you're a trained super spy. A slightly more positive message is hidden for the purposes of a "twist" in the movie's plot.
Heavy action violence, with lots of shooting, stabbing, fighting, punching, chasing, and explosions. The heroine is tortured in the opening scene; she's pummeled, and gasoline is poured down her throat. A man kills two guards with a shoe knife. Salt is shot and wounded; she stabs and kills a man with a broken vodka bottle. A flashback of Salt as a little girl shows her bruised and clad in bandages, as if she had been horribly beaten.
Some romantic kissing. In one scene, Salt removes her panties from under her skirt, using them to cover up and disable a security camera. She's also shown in her underwear during the opening scene. There's a shot of a Long Island bar called "Jugs and Strokers."
The most frequent words used are "goddamn" and "s--t." "F--k" is used at once. Also "Jesus Christ" (as an exclamation), "damn," and "hell."
One very prominent Pepsi billboard, a brief glimpse of a Heineken truck, and images of board games like Operation, Connect Four, and Othello.
The Russian spies drink a lot of vodka in a "background" way.