Yes, by definition, a light wave always travels at the speed of light in a vacuum. The speed of light in a vacuum is approximately 299,792,458 meters per second (or about 186,282 miles per second). This value is often denoted by the symbol 'c' in physics.
It is important to note that the speed of light can change when light passes through a medium other than a vacuum, such as air, water, or glass. In such cases, the light wave interacts with the atoms or molecules of the medium, causing it to slow down. This change in speed leads to phenomena like refraction. The speed of light in a medium is typically slower than its speed in a vacuum, and it depends on the properties of the medium.
However, when we refer to the speed of light, we usually mean the speed in a vacuum, where it travels at its maximum value and is constant for all observers.