AU is an abbreviation for Astronomical Unit. This is used by astronomers to describe Solar System distances. One astronomical unit (AU) represents the mean distance between the Earth and Sun. An AU is approximately 93 million miles (150 million km). It is approximately 8 light minutes.
More exactly, one astronomical unit (AU) is 92,955,807 miles (149,597,571 km).
When written in the form AU/h this means how many AU will be traveled in the span of one hour (60 minutes). So for example 2 AU/hr means a distance of 185,911,614 miles (299,195,142 km).