The slate was brought by Kelly to control the crying crypt, but it was stolen by the ghost fox, which can help Greer recall his memory.
After Ghost Fox analyzes the slate, the slate content is displayed in concave-convex characters, which can be translated.
Title-Bump Bible
Compare with the official concave-convex comparison table. I can see that the slate is in English (and the names of the contestants are all in pinyin)
The following is the translation provided by Luo Tian, a researcher at Bump Research Center.
AOTU bible
The concave-convex bible (.
originally
initial
There are no forms and words in this world.
The world has no shape or language.
Darkness enveloped the face. ...