Question

What is charge ? and what's the meaning of charge?

Answer 1

Charge is a property of objects. The total amount of charge and the charge distribution of an object determine its behavior in electromagnetic fields. +ive and -ive are (historical) conventions. In more simpler way,charge is a number, and the difference between positive and negative charges is the sign of this number. Charges from the same group will repel each other, and charges from different groups will attract each other. But which group we call -ive and which group we call +ive is a matter of convention.