Hydrogen ions, often represented as H+, carry a positive charge because they consist of only a single proton and no electrons. In a neutral hydrogen atom, there is one proton and one electron, which balance each other out, resulting in no overall charge. However, when the hydrogen atom loses its sole electron, what remains is just the proton—a particle that carries a positive charge.
This proton is what we refer to as a hydrogen ion. The loss of the electron, which bears a negative charge, leads to an overall positive charge for the ion. Therefore, when we say hydrogen ions are positively charged, we are simply highlighting that they are composed only of this positively charged proton.