Imagine you're at a party and you're trying to get someone's attention, but they're not looking at you. That's kind of like what the red arrow symbol means - it indicates that someone has sent you a snap, but you haven't opened it yet, and it's waiting for you to check it out.
On the other hand, if you see a purple arrow, it means that someone has screen-shotted your snap. It's like, you're trying to share a secret with someone, but they're taking a sneaky picture of it to show to their friends.
Now, you might be wondering, why should I care about these symbols? Well, they can actually be pretty useful in your daily life. For example, if you're trying to keep track of who's seen your snaps and who hasn't, the arrow symbols can give you a quick idea of what's going on.
What Do the Two Arrows Mean on Snapchat - SocialAppsHQ