The fastest thing in the universe, as far as we currently understand, is light. In a vacuum, light travels at a constant speed of approximately 299,792 kilometers per second (or about 186,282 miles per second) in a phenomenon known as the speed of light. This value is denoted as "c" in scientific equations.
It's important to note that when we refer to the speed of light, we usually mean the speed of light in a vacuum. Light can travel at slightly slower speeds when passing through different materials, such as air, water, or glass, due to interactions with the medium.
On the other hand, space itself is not a physical object that can move or have a velocity. Space is the framework within which objects exist and move. It's the three-dimensional expanse in which matter, energy, and events occur. So, it wouldn't be accurate to say that space itself has a speed.
To summarize, light is considered the fastest thing in the universe, whereas space is not a physical entity that can have a velocity.