Afsluit = "close off". Dijk = "dike" (pronounced the same too). It's a 20 mile long dike we've built that closes off what used to be the South Sea from the North Sea, turning it into a big lake that's called the IJsselmeer.
It's all the QWERTY home-row letters making it look that way, I think. Does look a lot like a quick slam of the fingers on the keyboard to generate a "random" string.
Apparently this is a real place, not a slamming keyboard word.