What does "three sizes" mean in this sentence?
My boots are three sizes too big for me.

Does it mean three centimeters, inches, or any other units of length?

Question

What does "three sizes" mean in this sentence?
My boots are three sizes too big for me.

Does it mean three centimeters, inches, or any other units of length?

Answer

It means that the shoe size is three measurements to wrong.  E. G my feet are size 10 but the shoes are size 13