Alright, first things first. You gotta have Firebase installed in your project and make sure the Remote Config service is up and running. You'll need to create a Firebase project and hook it up with your app. If you need a hand with that, the Firebase documentation has got you covered with all the nitty-gritty details.

Next up, let's talk about locales. To get your app speaking different languages, you need to define your locales. Usually, you'll start with a default locale, like English, and then add other languages or regions you want to support. Each locale will have its own set of translations stored as key-value pairs. Simple, right?

Now, head over to the Firebase console and dive into the Remote Config section. Here, you'll create unique parameter keys for every string that needs to be localized. It's a good idea to organize your keys, maybe by prefixing them with the name of the page or screen they belong to. Keeps things tidy!

Time to set the values for these parameters based on the locales you've defined. Each key will have a different value for each locale. For example, if you're translating a greeting text into Russian and English, you might have a key "greeting_text" with the values "Привет" for Russian and "Hello" for English. Easy peasy.

In the Firebase Remote Config, you can set up conditions that determine when a different set of parameter values is used. For localization, these conditions will depend on the locale of the user's device. Define a condition for each locale by selecting "User in app locale" and providing the corresponding language or region code. Piece of cake, right?

Now, in your app, use the Firebase SDK's fetch method to grab the remote configuration, and the activate function to apply it. This will update the strings in your app based on the locale conditions you set up. Pretty cool, huh?

Don't forget to handle the case where fetching the remote config fails. It might be due to the user's internet connection, or maybe your app hit the rate limit for config fetches. In these cases, use a local default configuration that matches your default locale. Better safe than sorry!

Finally, give your remote configurations a good test. Manually set different locales on your device and open your app. If everything's set up correctly, you should see the text in your app change based on the locale. And there you have it!