In U.S. military time, 1900 hours is equal to 7:00 p.m. standard time. The military uses a 24-hour clock that begins at 0000 hours, corresponding to midnight, and restarts after 2359 hours, or 11:59 p.m.
Military personnel often reference the local time where the base is located, observing Daylight Saving Time if that particular state or country recognizes it. However, when communicating with units in other time zones, the U.S. military references Zulu time, which corresponds to the time zone where Greenwich, England, is located. This avoids confusion and provides a standard frame of reference for bases all over the world.