I am not exactly certain but the gist of it is, the Polish Government wish to be the only authority who can offer a job as a judge and be the only authority who can take that job as a judge, away.
I probably have over simplified.
But essentially Poland wants to be Supreme in the control of its laws, Poland can not be Supreme over its laws if the E.U. claim higher authority.
So an impasse is reached.
As the E.U. imagines itself to be the Supreme Authority over Poland, they are trying to fine Poland.
Poland will not pay a fine to be Supreme in its own land.
Some are saying this could end with Poland leaving the E.U.
Hungary and Slovakia are backing Poland against the E.U.