Dear student,
pH means the potential of H+ ion in the solution , the formula is pH = - log[ H+ ]
Ph scale is the value of pH from 1 to 14 to decide the acidc or basic nature of the solution
e.g. if pH lying below than 7 solution ic acidic
If pH = 7 , solution is neutral
And if pH is more than 7 , solution is basic in nature
Regards