The skeletal structure of an organic compound is an abbreviated representation of its molecular structure, they are quick and easy to draw.
For example, the following image shows the skeletal structure of a compound:
The peaks represent the carbons. We must remember that carbon can have a maximum of 4 bonds.
Now, I will show you how is the structure of this specific compound:
This is ternary alcohol, called 2-methyl-2-butanol. If you see carefully, you will notice that each carbon has 4 bonds. The functional groups present will be OH. The skeletal structure will be: