Check out example codes for "how to store some variables on the device in unity". It will help you in understanding the concepts better.

Code Example 1

//Example using the PlayerPrefs system to store integers on the local device storage
//Writing data
PlayerPrefs.SetInt("myPref", 5);
//Reading data
myint = PlayerPrefs.GetInt("myInt");

Learn ReactJs, React Native from akashmittal.com