It means what it says:
You need to read up on that stuff and make sure your settings are consitent in the output module settings as well as in the Encoder itself. If you have audio, turn it on in both places. If your comp is an odd size, use a different MPEG Level.
By the way, the handling of these sorts of constraints is much better in the more recent versions of the software. Instead of just giving a cryptic message, the application does the correction for you and warns of the mismatch (so that you can apply a different correction if you'd rather).