What is a compound that has two halogen atom on adjacent carbon atoms is called?
A vicinal dihalide.
Vicinal means "neighboring" or "adjacent", and, well, dihalide means there are two halogenic atoms on those adjacent carbon atoms. An example is 2,3-dibromobutane.
(On the other hand, a geminal dihalide has the two halogen atoms on the same carbon. An example is 2,2-dibromopropane.)