It identifies you to other players in multiple games, including Minecraft. There are ways to change your Minecraft name on each platform and also on the Java and Bedrock editions.

How do I find my Minecraft username? On the change name screen, you can see your previous name located right after the field “Current Java/Bedrock Profile Name”.

How to change game modes in 'Minecraft: Bedrock Edition' In "Bedrock Edition," you'll need to enable cheats when you create the world - there's no way to enable them in an existing world.