The Prison.
Das ist = That is.
Was dedeutet das translates as what does it/that mean
Das Ende is German for the end.
(das) Pferd = (the) horse
Das Mutterschiff' = the mother ship
Was ist das = what ist that
das mag ich = I like that
"That is not" is "das ist nicht" in English.
In English, "das Kind" translates to "the child."
The answer is simply: "What is that supposed to mean?" and is a short form of the question "Was soll (denn) das heissen?" or "Was soll (denn) das bedeuten?"
"Welcher Tag ist das?" = "What day is it (today)?"
"ist das dein" basically means "is this yours"