So the empty set really has elements, and it has just subset (which is itself, the empty set).
It is like asking "There is nothing available, so what do you choose?" Answer ""
then we have a set with one element: {apple}
How many subsets does the set {apple} have?: the whole set ({apple}) and the empty set ( {} )
So any set with one element will have subsets.
you have a set with one element: {12}
one element will have subsets, and they are: { } and {12}