In English when we say someone goes overboard it can mean that they just fell off of a ship! But it can also mean when somebody does more than was expected of them, when someone does too much but in a way that makes other people kind of feel bad. So let's imagine you're going to a family dinner and your grandmother tells everyone, "Please bring one food item. Please bring one food dish." But you have an uncle who always brings ten. So he always brings too much. He always goes overboard. And this makes everyone who only brings one food item feel a little bit bad. So to "go overboard" is to do too much but in a way that makes other people feel bad.