Salam Alicom dear brother
Dreams are three types
1#Dreams that reflect our subconscious mind
2#Dreams that inform about good or important events
3#Dreams that warning of danger
Most of ours dreams are belong to the first type according ours psychological status
The others two types usually come as a clear short vision and gives the dreamer the feeling about its importance
Some times the dream can contains more than one type Anyway, the dreamer who can know is his dream look like a clear vision or just a nightmare that doesn't have any meaning
About your mentioned dream its looks like the first type
But Incase it has meaning, killing in dreams means that the killer oppress the person that he killed in something, or unfair him
and Allah is the only one who knows the facts