English privateers were private people or warships authorised by Elizabeth through the Lettres de Marque to attack foreign ships. This was very similar to how pirates operated.
What did the English privateers do?
Privateers would attack or capture treasure ships belonging to the enemy.
How was Elizabeth involved with the English privateers?
Privateers had to give a share of their loot to Elizabeth to gain legality for their actions. The amount of treasure she received from Sir Francis Drake, for instance, was huge.