With the array modifier i created 12 mesh and applied the modifier. And now i want to separate them to make them 12 mesh. But it creates a single verts only. Is there any other way or whats going wrong why i cannot create 12 mesh from it by the selection option
You've applied the modifier, so now you have one object, and inside this object you have several meshes that compose your different small cabins.
If each of your cabin is made of one mesh, in Edit mode, select all and separate with P > By Loose Parts and you will have 12 different objects.
If each of your cabin is made of several meshes, in Edit mode, select each object and P > Selection.