Hi Sai Kumar, If I have understood your question correctly, you are asking how come the lag 12 correlation in the PACF plot indicates a seasonal correlation of period 12, while the strong lag 2 correlation shown by the other PACF plot is simply a second day correlation i.e. an AR(2) process.

The reason the former plot indicates a seasonal process of period 12 is that correlations in the PACF are decaying out gradually at lags 24, 36, 48 etc. i.e. multiples of 12.

No such pattern is seen in the PACF plot that shows a strong lag 2 correlation. In this plot, the correlation drops off sharply after lag 2 which is indicative of an AR(2) process.