Polar and non-polar molecules - meaning and differences

For example, an electron has a negative polarity e- that means that it has a negative electric charge. An ion of sodium posseses a positive polarity Na+ meaning it positively charged. Atoms and molecules has both positive and negative electric charge, their polarity only comes because one state of electric charge is greater than the other. For example, an atom can be negatively charged. This means that it has more negative charge carriers (electrons) than positive charge carriers (protons). This makes it has a negative polarity. Same goes for positively charged atoms. Some atoms and molecules can be neutral (having no electric charge). 

Polarity is just a state of having a positive and also a negative electric charge, especially in the case of magnetic or electrical poles. That phenomenon of seperation of electric charges into positive and negative is what is defined by the term polarity.