The text states "There was very little social mobility during the Middle Ages." What does this phrase mean

You were born into your social class and stayed there

Explanation:

there was very little mobility because whatever class you were born in that's what you did so you had very little choice and say in what you wanted to do therefor you were put where you were born.

powers  are  denied  to the  national governmentin three distinct ways: some  powers, such as the  power  to levy duties on exports or prohibit the freedom of religion, speech, press, or assembly, are expressly  denied  to the  national government  in the  constitution.