Mac systems allow you to hide photos and videos to a Hidden album, making them disappear from your Library, albums, or even the Photos widget if you enabled it on your Home Screen. You can even turn off the Hidden album if you want that extra security.
Open the Photos app by opening Finder > Applications > Photos.
On the Apple menu bar, click the View button and click the “Show Hidden Photo Album” option on the dropdown menu.
In the sidebar that appears, click “Hidden.”
Select the items you want to unhide, then on the Apple menu bar, select Image > Unhide Photo.
To find the Hidden album, which is off by default, do the following:
Open the Photos app by opening Finder > Applications > Photos.
On the Apple menu bar, click View > Show Hidden Photo Album.