One coulomb is equal to the charge on 6.241 x 1018 protons. The charge on 1 proton is 1.6 x 10-19 C. Conversely, the charge of an electron is -1.6 x 1019 C.
A coulomb is an enormous charge - two 1 C charges that are 1 m apart exert a force of 9 x 109 newtons (see Coulomb's law). That's over two million tonnes, ~720x as much as the thrust of a space shuttle solid rocket booster during liftoff.
To learn more about the coulomb, click here.