I would call it an information board (https://wiki.openstreetmap.org/wiki/Tag:information%3Dboard).

Unfortunately I didn't take any pictures myself, but it looked like this today:
https://maps.app.goo.gl/raswAFBiscpNo9GF7?g_st=ac
https://maps.app.goo.gl/hEhYSzhpfM4g7Qjm8?g_st=ac
https://maps.app.goo.gl/6ysvsj5XMUo96Atv6?g_st=ac

The basin with the fish from the website could not be seen. If it is only placed there temporarily during the summer (from the website this wasn't clear to me), then the opening hours shouldn't be 24/7.