Speed of light as a cosmic speed limit

Light has one speed in empty space. Nothing carrying information beats it. Ever.

Definition

In vacuum, light travels at a fixed speed c of about 299,792,458 metres per second, the same for every observer regardless of their motion, and no information or matter can travel faster.

Step 1

Predict first

In one or two sentences, what do you think this concept means? Wrong is fine; the small struggle is what makes the answer stick.