First of all Navigate your default file manager settings and Check the box “Show hidden files/folder” Now Navigate to the file or folder which you want to hide in your smartphone.
Once you see the file on your Screen, Long Press it so that you can rename the file, Now just add a Dot (.) Before the file name and save it.
For Eg: if you file name is Image, Then you will rename it to .Image
You will still be able to see that file because we have Show Hidden files/folders Enabled. so our next step is again goto file manager settings and turn off Show hidden files/folders.
Now Navigate to the file that you renamed, You will not be able to find it because its now hidden.