Isn't this Wy zamknij-cie, and therefore, "You close this store"? Wouldn't "Close this store" be "Zamknij ten sklep"?
„Zamknijcie” is the second person plural imperative. „Zamknąć” is a perfective verb, so it doesn't have present tense.
This one really confused me at first because I thought that it was always just "Zamknij." I didn't know there was a plural version of it before these lessons, but I got it pretty quickly