The ability to remove the background from a picture on an iPhone can be achieved through various methods, including using the Photos app, Files app, or Safari browser. To use this feature, you need to open the desired image, tap and hold on it, and then select "Copy Subject" or "Remove Background". The subject of the image will then be automatically detected and saved as a new image in your camera roll or files app. This feature can be useful for creating stickers or pasting images into other places, but its limitations should be considered when using Safari browser to edit images directly from web pages.