A "mini backpack" refers to a smaller version of a regular backpack. It is a small bag with straps that goes on your back, used for carrying a few things around.
Sentences with «mini backpack»
I think even though I'm not going back to school I'm going to buy a cute mini backpack, maybe even today. (carriebradshawlied.com)
I can imagine this faux fur mini backpack paired with an all white look — white denim and a cream sweater. (thebrunettenomad.com)
dream on boater hat faux leather mini backpack [available in 2 colors, only $ 55!] (thestyledfox.com)