Iphoto deleting

Dumb question... When I try to delete a photo from my iPhone 6s or from my husband's iPhone 6, the message on the delete photo button states This Photo Will Be Deleted From iCloud Photo Library on all devices. Does this mean that the photo is gone forever from everywhere including iCloud Library (never to be accessed again)? My husband's iPhone has no memory left and we need to delete something but we don't want to delete & lose the photos & videos on his phone (lots of work pictures & vacation pictures). We've uploaded them to our MacBook Pro and it looks like they live in the ICloud Photo Library. Or should I just download/save them to an old-school thumb drive?