Hi @Mushtaq1, welcome to our forum and I'm sorry for my late reply. This is a standard notification that you will receive in your phone when you are running out of free space on the internal storage. If you have a SD card in your phone, you can move media to the SD card if you go to Settings > Storage > Transfer data to SD card. There is also a very nice guide here on our forum on how to free up space on the internal storage, it is however mostly suited for Android 6 and 7, however it will still work in earlier Android versions as well. https://talk.sonymobile.com/t5/FAQ/Free-up-storage-in-your-device-Guide-for-Android-Nougat-amp/m-p/1212614 I hope that helps!
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