we call em tuinhuisjes, literally , garden house
shack where the lawnmower and garden tools are
but it's to far from the garage to be of use as engine rebuild shop or something like that, no electricity either
it's not decorated on the inside
some folks have bigger ones, with better interior, as kids that used to be fun part of summer, go to uncle xxx, and camp out in his gardenhouse, he had a one with all bells and whistles