overwhelming

Something that's overwhelming is so big or intense that it feels like too much to handle.

Imagine you've just moved into a new apartment and it's still packed with boxes from the movers. You're feeling really stressed out because you have so many things to sort through and put away, and it seems like there's no end in sight. That's what people might mean when they say something is overwhelming - it's an experience or situation that's too much for one person to deal with, like trying to finish a huge project at work on top of your regular tasks, or dealing with a very difficult personal issue. It can feel like you're being swept away by the situation, and it's hard to stay focused or keep going because there's just so much to handle.