Hey kiddo, so in the Bible there were some people called 'destroying angels'. Now, these weren't really actual angels with wings and halos and stuff. It's just a way to describe something that happened in the Bible.
You see, sometimes in the Bible, God would punish people if they did bad things. And the 'destroying angels' were kind of like messengers from God, who punished these people.
One example is when the Israelites were wandering in the desert and they started complaining to Moses about not having enough food or water. God was pretty angry about this because He had already taken care of them by giving them manna and other things.
So, in punishment, God sent down these 'destroying angels' to strike down some of the Israelites. It sounds kind of scary, but it was just a way for God to show them that they needed to be grateful and trust in Him.
Basically, 'destroying angels' is just a way to describe an act of punishment from God in the Bible. Hope that helps you understand a bit better, kiddo!