Study the information about the 3rd Conditional.
Type 3 Conditionals.
This type expresses imaginary situations in the past. They refer to past situations that did not happen.

If + Past Perfect, would/could/ might + have+ past participle
Kate missed the plane yesterday. If she hadn’t missed the plane, she wouldn’t have been late for meeting yesterday.
If Mike had called earlier, I would have told him about the party.