Encoding is the process whereby the data for each video frame is compressed so that file sizes are manageable. See: http://en.wikipedia.org/wiki/Encoder
What help do you need beyond a definition? Note that MEP 13 is years and years old -- the newer versions have lots more features, and are generally faster and easier to use.
. . . . Note that MEP 13 is years and years old . . . .
Agree with Carl, however I think this could be case of mistaken identity - if your reference to MEP 13 should be MEP 2013, please use MEP 2013 to avoid confusion with the older version- unless of course you really do mean MEP 13