Yep - in the easiest way I can explain:

There are 4 different leagues: League A, B, C & D. Within each league are four groups. For example: League A1, A2, A3, A4. In other words:

**Group A1**: Germany, France, Netherlands

**Group A2**: Belgium, Switzerland, Iceland

**Group A3**: Portugal, Italy, Poland

**Group A4**: Spain, England, Croatia

Now the winners of all of the groups A (lets just say Germany, Belgium, Portugal & Spain as theyre the 1st teams there) will enter a knock out round of semi finals. They will be drawn at random - for example, Germany Vs Belgium & Portugal Vs Spain. The winners face the other winner - For example Germany Vs Portugal. The winner of that game is declared the League of nations winner and already qualifies for the Euros 2020.

It is the same format for League A, B, C & D. So 1 team from A, B, C & D will qualify for the Euros (hence the criticism that Luxembourg may actually qualify). 4 teams will qualify from this in total.

There are 24 teams in total for the Euros 2020 - 16 teams will qualify through the original qualifiers - so the normal group stages. The teams that already qualified for the competition will play in the normal qualifiers - if they happen to win their group then the next best team will essentially finish 1st.

So that makes 20 out of the 24 teams decided.

Now for the last part - if you finish last in League A - you get relegated to League B. And visa versa there will be promotions & relegation across the board. In the new divisions we now need that last 4 spots to be filled. But how Gassy? I hear you scream! So the most highly ranked teams of League A, B, C & D (that have not qualified yet) will enter yet another semi-finals type knock out stage. Again this will happen across groups A, B, C & D. The winner of A, B, C & D will qualify. So one team from each group again will fill the last 4 places.

At this point - all 24 teams are done and we move to Euros 2020.

Oh - 1 other thing, there is only 1 nations league winner - whoever wins the League A final - is considered the Champion.

I hope that explains in the simplest form?

You can view the groups here,

https://www.uefa.com/uefanationsleague/news/newsid=2530180.html