The p-values
pKA and pKB

mathematically:            p...... = -log .......

KA and KB are the acid / base constants, who's values can be find in tables.
Often the values of concentrations (certainly the mathematical products of concentrations) are extremely small, like for example: 10-6 mol/l.
Therefore were introduced the so called p-values; they make writing of and calculating with concentrations a lot easier.

KA and KB also often have very small values, like: 10-12 or 10-7
In chemical calculations and in the books we use the p-values 12 or 7

In aqueous neutral solutions with a temperature of 25ºC:
The following statement is true: pKw = pH + pOH

pKW at 25ºC has a value of ±14; at 100ºC that value is ±12

pH

Study the following scheme; try to understand it and to explain:

pH
-1
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
pOH
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
-1
very strong
and/or
concentrated
acid
solutions
acid
solutions
neutral
solutions
basic
solutions
very strong
and/or
concentrated
basic
solutions