“Cursed before Yahweh.” That is, cursed in Yahweh’s presence. The NLT gets the sense of the verse: “May the curse of the LORD fall on anyone who tries to rebuild the town of Jericho.”
“rebuilds.” The Hebrew word for “rebuild” here can be “build” or “rebuild” depending on the context. Here it is more properly “rebuilds.”
“this city, Jericho.” The Hebrew text places an emphasis on both “this city” and “Jericho.”
“will he lay its foundation…will he set up its gates.” After a miraculous victory and destroying the city of Jericho, Joshua spoke a curse over the destroyed city: “Cursed is the man before Yahweh, who rises up and builds this city, Jericho. With his firstborn son will he lay its foundation, and with his youngest son will he set up its gates.” That curse, which was also a prophecy, was fulfilled over 500 years later when Hiel the Bethelite rebuilt Jericho and offered his oldest and youngest sons as foundation sacrifices.
[For more information, see commentary on 1 Kings 16:34.]