The phrase "to need some salt" means that a person's food is lacking flavor and could benefit from the addition of salt to make it taste better. Full definition
You shouldn't need salt because of the sodium in the sauerkraut, but add some if you desire. (homespuncapers.com)
Although we do need some salt in our diet, too much is linked to various health problems including increased risk of stroke and cardiovascular disease. (scientificamerican.com)
The human body needs salt to survive, but in excess it can kill you. (visualnews.com)