Here’s the deal American British informal
1. Used to signal an explanation
Jame: "Why did she storm at you?" Marry: "Oh, here's the deal. She caught me red-handed while I was trying to hide her backpack.
Here's the deal: there is something wrong with our book, so I need some editors to go with me for a doublecheck before publishing.
2. Used to introduce an idea or plan
Here's the deal: I'll divert my Dad's attention away from the main door while you sneak out.
Here's the deal. You stay here to look after these kids, and I go out to buy some food.
To be thankful or grateful for one's good luck usually while avoiding a bad situation
You should count your lucky stars as you managed to avoid that violent car accident.