What should I do about salt in V-brakes?
If @ Daniel R Hicks suggestion doesn't work you might need some more intense maintainence. Remove the brake cables from the calipers. Then remove the brakes from the bike, disassemble them completely. Clean all the salt and corrosion from the shaft and the pivot holes of the brake arms. Lightly lube the pivot points and shaft (I am partial to white grease) with a small paint brush. Reassemble the caliper and remount. You may want to do just the front first, that way you have the rear as an example if you get confused during the reassembly. Once everything is cleaned up, a periodic rinse and relube should keep things moving.