It's been reported that these files contain details about the Facebook data delivery solutions which led to the Cambridge Analytica scandal. In particular, they encompass e-mails between executives and correspondence with Facebook CEO Mark Zuckerberg.
According to the order of the California court, the publication of files in the United States was limited. Facebook has already made a request to the UK committee to do without reviewing the documents and return them to the social network. But the Zuckerberg company cannot actually influence this since the Parliament of England operates under its jurisdiction.
Zuckerberg himself will not testify before an international committee at the hearing on November, 27. Vice-president Richard Allan will speak instead. The UK government may have quite some questions about the confidentiality of social network data in a detailed study of all the documents received.