explain the haloalkanes in the easy way

Haloalkanes or Halogenoalkanes are compounds in which one or more hydrogen atoms of an alkane have been replaced by halogen atoms (fluorine, chlorine, bromine or iodine). 

Few examples:

Depending upon the position of the halogen atoms, the haloalkanes are classified as primary,secondary and tertiary.

In a primary (1°) halogenoalkane, the carbon which carries the halogen atom is only attached to one other alkyl group.

In a secondary (2°) halogenoalkane, the carbon with the halogen attached is joined directly to two other alkyl groups, which may be the same or different.

Examples:

In a tertiary (3°) halogenoalkane, the carbon atom holding the halogen is attached directly to three alkyl groups, which may be any combination of same or different.