Would you be kind to provide some example with "controversies" and tell the difference between controversy and controversies?
When we say things like "There has been a lot of controversy about gun control," "controversy" is being used in its uncountable sense. The meaning is that gun control, or the question of whether there should be gun control, has been very controversial; it is a topic on which there has been a great deal of debate, with people arguing on both sides.
When we say things like "The current controversy over whether whether we should have gun control is nothing compared to earlier controversies concerning abortion and euthanasia," "controversy" is being used in its countable sense. The reference is to separate instances of controversy, separate debates or sets of debates about particular matters. ♣