The alarm sounds on the specified date and day.
When you use WiFi, it is backed up to Google Drive every 24 hours, so data is automatically maintained when you reinstall. (Android 6.0 or later)
2b7cb8fbada727b456df828271ac44ab
F4:8C:2F:68:0F:AA:35:71:D1:61:7B:B3:B3:9