This is a German works council, which is the most common outcome of a unionization effort: https://en.wikipedia.org/wiki/Works_council#Germany

Its creation can be forced by a vote of the employees and the council has a legal special status. This probably comes as a reaction to multiple distribution centers around Germany doing exactly that and forcing the creation of local work councils with the help of unions.

It's a common thing in German companies of all sizes and usually a good thing for the company too because problems between management and workforce are usually solved in a much less "confrontational" way compared to full-blown unionization (especially in smaller family-owned "Mittelstand" businesses).

Unions and Works Councils are not mutually exclusive. All companies that have a recognized Union will have a Works Council too.

A Works Council is entirely company specific. A Union is usually concerned with an entire sector and deals with company-specific issues only a limited way. In practice the Union organisations often provide assistance and advice to a Works Council, even to companies in which they are not active as a Union.

You might want to research German employment law a bit more...

Often union members are elected into works councils.

It's basically like a government of the company and a union is just another party that can get elected.