Those are the three branches of the U.S. government, but in this context, they mean the three institutions required to pass legislation; a bill must go through both the House and the Senate and then be signed by the President to become a law. If Democrats had taken one of those institutions, they could have slowed the Republicans' agenda..
When they talk about a "trifecta" in this context it means the presidency, the Senate and the House. That applies to both the national and State governments.
Yes. The confusion is in the wording, not the message itself.
We already know they have the presidency and SCOTUS. The third piece of the trifecta is Congress. They already have the Senate. We’re just waiting on confirmation that they have the House as well.