The Photos app for iOS, iPadOS, and macOS has a special album called Imports. It has the useful purpose of showing what media you imported into Photos and when that import happened. This can sometimes help you track down whether you imported externally stored images and video, or which batch of media a particular item was part of.
Should you delete items from the Imports album to free up space? No! The Imports album, like other system-created albums, albums you create, and smart albums, references photos and videos from a central database managed by Photos. Imports, like these other albums, are a view into your Photos library rather than a duplicate set of your images and videos.
Selecting one or more media items in any of those albums in macOS and choosing Image > Delete X Photos/Videos will prompt the app to warn you that the deletion will move the item into the Recently Deleted album. You can also Control-click/right-click the items and select the Delete option from the contextual menu. In iOS and iPad, you get the same warning if you select one or more images and tap the Trash icon at the lower-right corner of the screen, or when you touch and hold a photo or video and choose Delete.
Read more at Macworld.com