To use a variable from one file in another file in a React Native application, you can export the variable from the first file and then import it in the second file.

In the first file (e.g. “File1.js”), you can use the export keyword to make the variable available for other files to use:

export const myVariable = 'some value';

Then, in the second file (e.g. “File2.js”), you can use the import keyword to access the variable:

import { myVariable } from './File1';

You can then use the myVariable variable in the second file just like any other variable.

Keep in mind that the file path in the import statement should be the correct path to the file where the variable is exported.