According to Encyclopedia Britannica, in the SI and the metre-kilogram-second-ampere systems, "Coulomb" is the unit used to measure the electric charge on an object. It is defined as amount of electricity transported by one ampere current in one second. One Coulomb has approximately 6.24 × 10^18 electrons.
The unit is named after French physicist, Charles-Augustin de Coulomb, who is also known for formulating Coulomb's Law: electric charge can neither be created nor destroyed, and can be either negative or positive. Also according to this law, objects that have the same type of charge repel each other, while objects with opposite charges attract each other.