Reload, also referred as Rld, Reload time or Reloading Time, determines the time your cannons need to reload. Every cannon (type) has it's own reload time and damage coupled to that. Check Damage Per Second for more information.
Reload in PotBS is giving in seconds (secs or s). You can increase your reload with the following:
TIP: use Crew Focus:Gunnery (skill) if you want a passive (cause everyone has it) buff to your reload!
Some Debuffs will decrease your reload time, same as some Fittings* will also make your reload longer.
*Do note that Reload is subject to Stacking Penalties.
Reload can NEVER exceed 100% of the cannons base reloading time. For example: a 18lbs cannon can never be reloaded faster than 21 seconds (42 seconds is base). Their are two (2) exceptions, both by the Naval Officer; Ultimate Ratio Regum and Final Offense. These Skills push the reload time beyond 100% (200% for Ultimate and 900% for Final Offense, but both only for 5 seconds).
This information is provided by the update that PotBS Wikia is undergoing, by Captain Vuur.