This is a lamentation for the princes of Israel, and it's basically a gigantic allegory explaining the defeat of the tribe of Judah and the royal House of David, a.k.a. the royal lines of Israel.
Ezekiel says that the people's mother was a lioness who raised a young lion.
The young lion learns to catch prey and eat humans, so the nations catch him and send him to Egypt. (This probably refers to King Jehoahaz who was exiled to Egypt a couple generations ago, as narrated here.)
The lioness takes another of her cubs and makes him a young lion, too.
He also learns to catch prey, eat people, and destroy towns.
This young lion is also captured by the nations, who send him to Babylon this time. (This is probz King Jehoiachin who got turfed to Babylon with the other elites shortly thereafter, as narrated here.)
In addition to being like a lioness, the people's mother was also like a vine, which grew a strong stem that became like a ruler's scepter.
But this stem was plucked up and thrown down where it dried out and its fruit died. Now it's transplanted in the wilderness, in a dry and thirsty place.
Basically, this is where Ezekiel gets all metaphorical, lamenting that Israel's leaders are doing a lame job at living up to their royal promise
It doesn't look like a scepter anymore.
Ezekiel repeats that this is a lamentation. Not an episode of "Animals Gone Bad."