Create a folder with a name you'd like, and add "." before other characters along the file name and save.
file name is Document, then it'd now become .Document
Your smartphone should notify you that the folder will be hidden
2. CLICK OPTION TO HIDE OR UNHIDE THE FOLDER
3.COPY THE FILES TO THE FOLDER YOUR CREATED
Copy the files you'd want to hide to the folder you created and it will be hidden, take for instance pictures or videos you wouldn't like to be displayed in your gallery once they are moved to this folder you created it wont display there again
4. GO BACK TO STEP THREE IN ORDER NOT TO ALLOW PEOPLE ACCESS THOSE FILES FROM YOUR FILE EXPLORER