Answer:
They provide background information to help the reader understand events.
Step-by-step explanation:
Flashbacks talk about a previous event, meaning they can explain the current situation in some way, shape, or form, be it how a friend was made or why so-and-so hates bars.
However, internal conflicts could be a good second answer as it could answer the question of why this is such a big deal (I.E. why being forced to throw out a rose when it was touched by a crush during a herbology lesson or something is something the protagonist doesn't want to do despite the fact it's been dead for weeks, though, again gives context for why said rose is important).