A lunar eclipse is when earth get into a position right between the sun and moon. As a result, earth's shadow would cover moon and for a short time moon can totally or partially go dark. It gets really dark if it's full eclipse. This may go anywhere from a few seconds to a minute or two.
The eclipse is for everyone to see if you want to get up and watch it, dependant on where you live is dependant on the time you can see it. I live in tennessee, we are central time and we are told that it will be visable between 12:43 to 2:00 something. Google the eclipse to get the exacts on what happens, too long to explain but it hasn't happen in 700 years.