For example, electrons are negatively charged and protons are positively charged. However, we cannot strip the charge off say an electron and leave bare a neutral electron . The charge is apparently part of the fundamental make-up of an electron. We have an operational definition for charge, that is, we define charge by what it does, not what it is. This has important consequences for the structure of the Universe.
Charge is quantized.
The signs are by convention. The unit of electrical charge in SI units is the Coulomb . 1 Coulomb is a huge charge.