What does the word "Dan" on the plaque mean?

Gudan tradition: it is the name of a natural village.

"Geography in the Book of the Tang Dynasty" said: In the third year of Wude (AD 620), Heyang was analyzed and Gudan County was established, and four years was the province. "Later generations called it" Gu Erdan "and became a village. So far, it has been renamed as "Guo Dan", otherwise people from other places will ask about its village and no one will know.

Extended meaning:

Dan (Gu Erdan): It's a sunny day. In the past, it was often used as a synonym for auspicious days.