a enlish learner

"Offhand" (notice that it's one word) means "without preparation." For example, in the sentence "I made an offhand comment" means I made a comment without thinking about what it might mean or how it might be interpreted by others.

"To have the upper hand" means "to have an advantage." If you are quicker and taller than I am and we are playing basketball, then you "have the upper hand." If we are playing chess and I have only four pieces left on the board while you have all of yours, then you "have the upper hand."

"Out of one's hand" is not a common expression, but it can be used literally. If you're holding a cup and you drop it, then you would say the cup fell "out of your hand." If you feed an animal by letting it take the food from your hand rather than putting the food on the ground, you are feeding the animal "out of your hand."

"Out of hand" means "out of control." If a situation gets worse and worse, you would say the situation is getting "out of hand."