Dreams about blood can have many different meanings depending on other elements in the dream. Similarly, dreaming of one's niece could mean many different things depending on what the niece is doing in the dream. A basic principle in understanding dreams is that the dream is about the dreamer, not about other persons that appear in the dream. So the blood and the niece in this dream reflect something about the dreamer's feelings, memories or experiences.
Assuming that the niece is well at the time of the dream, it probably uses the niece as a symbol for the dreamer or some part of the dreamer's life that is not entirely what it should be. For example, if the niece has a very active social life, the dream might be showing that the dreamer needs to get out and mingle with friends more often. > Alternatively, if the niece is not particularly healthy, the dreamer's mind could be picking up on subtle clues among family members that point toward an illness not yet announced publicly.
The taste of blood in this dream is a powerful metaphor representing your feelings of guilt and responsibility.
In this dream, the blood could represent your health. Carrying the blood in the bag might suggest that you are taking chances with your health.
It mean you had a bad dream.
Your niece is the daughter of your brother or sister.
You will lose something minor/major. (an object, person, friend or etc...)
My lovely niece
It is impossible to provide any meaningful interpretation without further information about the specific dream. "A man" could refer to anything from an astronaut to a cowboy, a stranger or a movie star or a bum on the street. Each example would carry a completely different meaning, depending on what that "man" does in the dream.
You probably mean Yahweh Nissi which means Yahweh is my banner,
it means you are having a nightmare and nothing else.
This dream suggests feeling as if someone is trying to cast blame on the dreamer. It reflects the expression of having "blood on one's hands."
That could be your daughter. It could also be someone with no blood relationship to you if it is actually your brother-in-law's niece. It could also be your niece and in most families you would just refer to her as a niece.