What is the shutter speed and aperture commonly used in general SLR?

There is no fixed number. The shutter has a safe speed, which is basically the reciprocal of the focal length. For example, if the focal length is 50mm, then the safety shutter is 1/50. If it is lower than this speed, such as 1/20, the picture may be blurred due to jitter. The aperture value depends on your subject. If it's a landscape photo, it's better to be above F6, and generally not more than F 1 1. Of course, it can also be F22, but it is difficult to control, which is beyond our control. If it's a portrait, it's usually below F3, which tends to blur the background and highlight people, but not every lens can reach such a large aperture, so when taking a portrait, try to adjust the aperture as large as possible, above the second stop of the maximum aperture of the lens.

It is recommended that you usually shoot with shutter priority (first gear). You control the aperture and let the camera decide its own shutter.