It means what every single other dream means.
Your brain pulls together all of your experiences and throws them in a blender and hits frappé. Some of those are new experiences (and often there are more of them in dreams), some are older. A lot are trivial, but the mechanism by which we dream doesn't know that. Hence, you might see someone in a dream who you think you know but the reality is it's someone you saw walking down the street 6 years ago, and you barely even noticed them then.
The big dream milk shake also tends to contain anxieties and good times or wishes, too. You dream of having friends and it's the latter. You dream of being chased by a serial killer, and it's the former. Symbolism may or may not factor. Special thoughts and meanings probably do, so if you love horror moves, dreaming of being in one might not be a manifestation of an anxiety at all.
So that's what it means. It means your subconscious works and it gave you a dream (probably several short ones - our brains tend to try to create a narrative around a bunch of super-short dreams). Tonight, it'll give you more dreams.