I’ve never completely understood the meaning of the lame- duck term. What exactly does that mean in regard to how the congress operates?
The lame-duck session is the session that immediately follows an election (usually just a few days after election day). It lasts until that session ends with the adjournment of that Congress and the installation of the "new" Congress on the first Monday of January.
Typically, the lame-duck session last from the first week in November to the time that the Congress breaks for Christmas. So, we're talking roughly 6-8 weeks.