When you connect to public WiFi, your phone constantly sends and receives information like a two-way conversation with the internet. Normally, this stays private between you and the website you're using.
But on an unsafe network, someone can slide right into the middle of that conversation without you knowing. This is called a Man-in-the-Middle Attack.
A Man-in-the-Middle attack is when a hacker secretly positions themselves between you and the website or app you're using like someone eavesdropping on a private phone call, except they're on the line the whole time.
Once in the middle, they can quietly read your messages, steal your passwords, or even change what you see on your screen all while you keep browsing normally, completely unaware someone else is in the room.