The company's ownership is divided in shares, also called equity. A cap(italization) table details the distribution of equity. In this example, 40.8% (= 51% * 80%) for founder 1, 39.2% (= 49% * 80%) for founder 2 (assuming it's OP), 10% for investor and 10% for something called options that may be granted in the future to new employees that allows them to buy shares of the company at a low price. 4-year reverse vesting with 1-year cliff means that if one of the founders leaves before 1 year of signing the contract, they are forced to sell at no profit (still, not $0) the entirety of their shares to the other shareholders. After 1 year of staying at the company, they may keep 1/4 of their shares and are forced to sell only the rest. Following that 1 year mark, they earn the right every month at the company to keep ~0.833% (= 40% / 48 as there are 48 months in 4 years) of their shares and forced to sell the rest. At the 4 year mark of staying, they are no longer forced to sell any of the initial set of shares. It does not apply to any future grants for which new conditions or new schedules may apply.