premise: A couple sitting at a reception table, the man is laughing as he motions back and the woman is laughing motioning forward. hypothesis: A man and woman are making gestures with their hands.
entailment: A couple generally refers to two people who are linked together emotionally and may or may not be of the opposite sex.  A man and a woman could be people who are together or not together.  The man laughing as he motions back and the woman laughing motioning forward can be different than making gestures with their hands.