How does solar electric propulsion (ion propulsion) work?

What does electrically charged mean?

All matter in the universe (anything that has substance) is made of small components called atoms. Every atom is made up of tiny particles called electrons protons and neutrons. Electrons repel other electrons, but are attracted to protons. Protons repel one another, but are attracted to electrons. Neutrons neither attract or repel anything.

Generally, the number of electrons and the number of protons in an atom are equal to each other. When that happens,the atom is in a normal or neutral state. An entire atom becomes electrically charged when the number of electrons or protons stops being equal. The "extra" electron or proton isn't balanced by something inside the atom anymore and begins to be attracted to the protons or electrons in other atoms.

What is an atom?
What is an ion?
What are other ion using technologies?
How does solar electric propulsion (ion propulsion) work?
Where does DS1 get its electricity?

How are atoms charged?
What's an electron?