What is a positively charged subatomic particle?
Protons are positively charged, massive nuclear particles.
And the number of protons in the nucleus defines
I have written before that the sign of the charge of the proton, formally positive, is arbitrary. The point is that the nuclear proton has an opposite electronic charge to the electron. It would make much more sense had the electron been assigned a positive charge (and thus necessarily the proton would have a negative charge).
Such a designation would have saved generations of quantum chemists from getting the wrong sign on their answer simply because they counted up the number of electrons wrong, i.e odd versus even, or vice versa. Of course particle physicists would then face the same problems that quantum chemists do; however, particle physicists are a lot fewer, and a lot weirder.