Gauge refers to the spacing between the rails.

In the US that's 4'8" and any track spacing that's wider is called "broad gauge".

1.676m,1.00m

Broad gauge railway track is appproximately 5-foot 6 meters wide

Because standard gauge is 4'81/2" and 5'6" is wider.

Meter gauge tracks are one meter or 39.4 inches apart.

Standard gauge rails are 4 feet 8 and one half inches apart.

Broad gauge is 5 feet between the rails.

Most USA railroads use standard gauge although Broad gauge was common in the American South before the Civil War. It is still common in many parts of Russia.