In the Hero system, movement is measured in meters per phase. Meters aren't used in the U.S. culture. Phases are "measured" by speed (SPD), and phases are within turns, which last 12 seconds. The number of miles per hour achieved by a character is dependent on their movement (purchased or unpurchased) and their SPD characteristic. This chart, when printed, provides a handy reference to know how fast, in U.S. terms, a character can go given these two variables.
Since normal humans are given SPD 2 and running at 12 m, you can see this computes to about 4.5 MPH, which an average, healthy, human adult can run.
The chart is also helpful if you want to build a character that moves a certain number of miles per hour. If you have already bought the character's SPD, then you can do a reverse look-up and buy the appropriate movement in meters for the movement ability you are building (such as flying, swimming, running, or tunneling, etc.). For instance, to fly at 40 miles an hour, you buy about 70 m of Flight at SPD 3, about 55 m of Flight at SPD 4, about 45 m of Flight at SPD 5, etc.
You are also free to change the Movement column values, and the whole grid will update to reflect your changes (it IS Excel, after all).