thank you very much for your comment. Indeed in the article there was an error, which I have corrected.
The correct sentence is the following one:
In the PACF graph the maximum lag with a value out the confidence intervals (in light blue) is 12, thus we can set P = 12.
There was a similar error for Q.
In practice, the value of P and Q should be chosen on the basis of the X axis (which represents the lag) and not on the basis of Y axis (which represents the auto correlation or partial auto correlation).
Hoping this helps.