Learners who know the definition but not the usage.
You may understand what the word means, but still not know how it sounds in a real sentence or when it is natural to use.
Students working from questions, options, or word lists.
A difficult word can appear in a problem, answer choice, or vocabulary list without any helpful example. You want to see how it works in an actual sentence.
Learners who want more than a single definition.
A translation alone is often too thin. You want a sentence that gives the word context, so it is easier to remember and easier to use later.