is their in electrons and protons that they acquire change?
And what is the charge actually?
Your questions are very vague.
I want to know the definition of the charge and why do electrons & protons have charge.
I guess the definition depends on what theory you are interested in. If you are working with QM then charge is the conserved quantity corresponding to the U(1) gauge symmetry. If you are working with classical EM then it is probably best defined by the Lorentz force law, however that might be a little circular if you use the Lorentz force law to define the fields also.
Or in a practical manner (my preference) you could define charge by an experimental procedure for measuring it. E.g. using the SI standard experiment for measuring an Ampere.
That is part of the definition of an electron. For the proton, it is because it is composed of quarks and having charge is part of the definition of a quark.
Charge is a fundamental property of some particles. This is similar to asking why do electrons and protons have mass. They just do.
So, is it a meaningless question?
I do not think it is a meaningless question. I think that it is just difficult to answer.
Charge is a property of subatomic particles. It defines the energy difference either positive or negative.
can we explain this property just like we can explain the properties of light?
What properties of light that can be explained? The existence of E and B field components? It's spin of of 1? It's energy?
For reference :
https://www.physicsforums.com/showthread.php?t=25666 (locked though) , sorry mentors and mods for quoting it.
Google : Discovery of electrons , protons and neutrons.
I think these huge list of sites are enough to satisfy you , I hope.
Separate names with a comma.