Microsoft Purview settings that retain, delete, or retain and then delete content. A retention policy applies the same rule to a whole location; a retention label applies to individual items and can declare them a record.
In SC-900 the principles of retention are tested: retention wins over deletion, and among several periods, the longest wins. Records management uses retention labels to declare records and disposition reviews.
Retention policies and labels is a concept that can show up on the exam. Check the full guide to see it in context.