The word therefore
in Jeremiah 19:6 introduces a further word of judgment from the Lord against Judah. The days are coming when this place shall no more be called Topheth, or the Valley of the Son of Hinnom, but the Valley of Slaughter.
The valley where Judah offered their children as sacrifices to Baal shall become a place of slaughter. This is probably a reference to the fact that many bodies would be buried there when the Babylonian invasion takes place (Jeremiah 19:11).
6 therefore, behold, days are coming, declares the LORD, when this place shall no more be called Topheth, or the Valley of the Son of Hinnom, but the Valley of Slaughter.