What problems do Symbols solve in JavaScript, and how do well-known symbols like Symbol.iterator, Symbol.toPrimitive, and Symbol.hasInstance let you customize language behavior?

Imagine you have a secret sticker that only you know about. You can put it on your toys to keep them special, and no one else can accidentally use the same sticker. Symbols are like those secret stickers in JavaScript—they let you hide special properties on objects. Well-known symbols are like magic stickers that JavaScript itself understands, like a sticker that tells a toy how to be counted or turned into a number.