Mac storage basics · Photos, music and video
Why is my Pictures folder so big?
Short answer: Usually the Photos Library inside it, which holds your whole collection. Manage it in the Photos app — delete and empty Recently Deleted, or move the library — never by editing it in Finder.
Almost always because of the Photos Library — your whole photo and video collection lives in that one item inside Pictures. Other libraries live there too, such as Photo Booth, plus any images or exports you've saved directly.
Don't open the library and delete things inside it; manage photos within the Photos app. To shrink it, delete what you don't need (then empty Recently Deleted), or move the library to an external drive. See where the Photos library is stored and why the library is bigger than your photos.