charge is a fundamental property of matter that is very difficult to describe in physical terms, you find electron , quarks etc have charge , but if you break electron or quarks ( which is a fool thing to say i.e they are elementry particle ) you are not going to find any separate thing like charge. types of charge is some different question that can be described
as you can call them +tive or -tive as they are antagonastic.But it is totally upon you which you will choose as +tive or -tive.So as by convention we had chosen charge on electron
as -tive.
but i don't think that you are asking any thing about the types of charge , but you are looking for true meaning of charge.But i don't think that anyone can fully describe it in physical terms.