1. Will I interpret the lag of 3 in this scenario?

2. If the hypothesis is positive (stationary) and shows that;

The likelihood that a result or relationship is caused by other factors, other than chance to some degree is very high, in addition the ACF does not drop to zero quickly. Blue lines in these plots often indicate 95% confidence intervals. Hence, there’s 0.05 ( 1:20 )probability that one of the lags will be significant due to random chance. Only one of 4(15) lags (excluding the first lag, which always equals 1) shows significance which spike (move beyond the insignificant level)

What are the further explanations for these results?