Premise: "A man in blue shorts and sitting in the pool watches a boy get out of the water."
Hypothesis: "A man is keeping an eye on his son in the pool."
Do we know that the hypothesis entailed by the premise? Stream of thoughts:
A man may be sitting in the bool watching a boy get out of the water but that doesn't necessarily mean that the boy is is own son.
Therefore, the answer is it is not possible to tell.