Potato chips and sea captains are salty. Salty can mean literally covered in salt like those delicious chips, or just crotchety, like a foul-mouthed skipper.
You can't drink sea water because it's so salty — but it may be hard for you to eat certain foods when they're not salty enough. Colloquially, you can use this adjective to mean "down-to-earth," "aggressive," or "exciting." So for example you could describe a movie pirate who's tough and blunt-spoken as salty. The "exciting or provocative" meaning dates from the 1860s, from the sense of "giving life or strong flavor."