What does "aperture priority" mean on the camera?

Aperture priority is to manually define the aperture size, and the camera will decide the shutter speed according to this aperture value.

Because the aperture directly affects the depth of field, this mode is most widely used in ordinary shooting. When shooting portraits, we usually use large aperture and long focal length to blur the background and get a shallow depth of field, which can highlight the subject. At the same time, a larger aperture can also obtain a faster shutter value, thus improving the stability of hand-held shooting. When taking photos such as scenery, we often use a smaller aperture value, so that the range of depth of field is wider, which can make the distant and nearby scenery clear, which is also applicable when shooting night scenes.