eslint vs tsconfig in react-native

Does anybody explain the difference between eslint and tsconfig for me?

module.exports = {  root: true,  extends: '@react-native-community',  rules: {'sort-imports': 'error',  },};

As far as I know, eslint just run with lint script, not having red/yellow underline to notify violating rules in file. But tsconfig does apply to ts/tsx file it rules with red/yellow underline.

Thank a lot and having a good day.