why my react native become .tsx instead .js

so after installing react native using npx react-native init MyProject the project is running and open in emulator but the app file is not app.js instead app.tsx,

file strcuture

The question is i am new to react native and many tutorial i see is havgin App.js file, and the code in app.js is different between js and tsx at least that's what i see, or is it just the same if i follow tutorial like folder structure, syntax and everything.