How to switch the frontend to Russian?
Changing a store view's locale:
1. Open the 'Dashboard' control panel.
2. Go to STORES -> Configuration.
3. Select the required 'Store View'. If you have only one store view then the changes will take place in 'Default store view'
4. Confirm the changes.
5. Select Russian.
Full path: 'STORES ->Configuration -> GENERAL -> General -> Country Options -> Locale Options ->Locale'
6. Save your settings by clicking on 'Save Config'.
7. Go to SYSTEM -> Cache Management.
8.Flush Magento's cache.
The frontend language for the current shop view is changed to Russian.