The easiest examples from mainstream languages are things like Result<T>, Future<T>, or Option<T>. Its honestly a very broad and vague way to say "some data with context". The advantage is that instead of using things like exceptions or panic/crash, your code must handle every case in order to get at the value unlike the normal case.

For example, an Option<T> could force you to unwrap the value and deal with errors. In true functional languages and/or where pattern matching is used, you must handle both cases, presumably creating a chain of "monads" all the way down (as most of your functions will return Option<T> or Result<T, Err> type patterns, since you can't throw an exception, and any value might be empty/error, so you have to propagate it upwards).

Honestly its a fancy term that functional programmers use to cow the laity. Its a bit like calling an if statement "probative procedural data query with indeterminate flow control."