Let's analyze it.
You will dream of your dead grandfather, which means that your grandfather has a certain position in your mind, otherwise you will never forget it; You may not have had a dream about grandpa for a long time, so you will be a little scared or disappointed; You dream that your hand is bleeding, which means that you may have suffered some physical injuries recently.
In fact, this kind of thing, dream, is a kind of association at the subconscious level, and it becomes a manifestation of entity in the dream. It is caused by various incentives, so don't think too deeply. If you have to struggle, it can be understood as worrying about the injury of your elders, etc., but it may not be realized. For example, on Monday, I dreamed that the stock rose sharply, and as a result, I didn't hold 4900 points. Holy shit.