Does lift generation create a vacuum over an airfoil? According to Bernoulli’s principle, airflow speeds up over an airfoil which decreases the pressure, and I read somewhere that when airflow speeds up over an airfoil, this creates a vacuum. Is this statement true?

How would a vacuum above an airfoil be different from airflow separation?
I think this is simply a terminology issue. 

There is no vacuum in the physical sense on the upper surface of an airfoil. There is an area of low pressure, though, which in certain context is also called a vacuum. 

A great example for this linguistic imprecision is my vacuum cleaner, inside of which there is no vacuum in its physical sense by far, but clearly it sports considerably lower pressure than the atmosphere in the rest of my living room.