To see a full list of all stats available in Blade and Soul, check out the Stats page.
The block stat is used to computed the damage reduction, the improved block (active) , and the block rate (passive). All stats can be compute using the formula %=(Block+B)/(M*Block+A). The values for these stats varies by class but are very similar between classes. The maximum damage reduction is quite low about 45% and suffers large diminishing returns over 700. The cap on the block rate is close to 97% assuming infinite stat points.