Here are some examples:
* "I brought everything but the kitchen sink." This means the speaker brought a lot of things, but did not bring a kitchen sink.
* "She has everything but confidence." This means the person possesses many qualities, but lacks confidence.
* "The store had everything but the specific brand of coffee I wanted." This means the store had a wide selection of coffee, but not the specific brand the speaker was looking for.
Essentially, "everything but" sets a broad scope and then specifically excludes something within that scope.