What do they mean by "creature?"
Probably something along the lines of the 'Beast' from Revelations, going on the apparently prophetic nature of the sentence. This is a wild guess on my part, though.
It is. And its not ... I guess.
There is no distinct description for it in Islam. However it is said that its like nothing a man ever laid eyes on And it can also speak in a way humans understand. And its purpose is to roam the earth , marking humans with their true faith. And ( In a weak Hadith , it is said that it engrave one of two words upon a human's forehead. " Muslim " or " Kafir ".)
Some say it will aid Muslims in their final battle against the infidels.
But the important thing about it is that the rise of this Creature marks the begginning of the final days of humans before Judgment day.
And it is one of ten signs that accompanies it.
1- The sun rises from the west.
2- Rise of the Antichrist.
3- Descent of Christ from heaven.
4- Rise of the ' Creature '.
5- The Sky covered in smoke.
6- Rise of Gog & Magog. ( Ya'jooj & Majooj in Arabic )
7- A landslide in the east.
8- A landslide in the west.
9- A landslide in the Arabian Peninsula.
10- The gathering fire that surrounds humans and guides them to the gathering place.
They aren't supposed to happen in this order. No one really knows which one will be the first. But they say once the first sign happens , the rest will follow rapidly.
I admit that I enjoy talking about such things. But there's always conflicted sources about the truth in how these signs would happen. But everyone agrees about the names.