Shutter speed is the time in which the curtain that covers the sensor opens and lets the sensor “take the photo” before closing again.
A longer shutter speed means the camera can take longer to take the photo and by longer it is still a very short time. Having this longer shutter speed gets you motion blur, because an object/s change its position during the time the shutter is open.
This Cheetah picture you can see the fast-moving parts (legs) are blurred and aside from its stance show it is moving at speed
A fast shutter speed makes the image sharp and doesn’t show movement this suits most photography needs.
Since shutter speed controls light into the camera sensor it then also has an effect on exposure (light). Quicker means less light in makes the image darker with a longer shutter speed floods the sensor with light that has a flow on effect in the image.
Shutter speed is measured in fractions of a second, your camera may do something like 1/3000th of a second or up to crazy quick 1/7000th of a second. On the long end 30 minutes is possible. Different to aperture relying on the lens shutter speed is the camera’s advancement to the extent of what shutter speeds you can do.