A personal communication could be an email, your own lecture notes, a phone call, a discussion or an unrecorded presentation - essentially it is a source which is nonrecoverable and unable to be accessed by readers. Therefore, a personal communication will have an in-text citation but no reference list entry.
No information is required in the reference list as the data has not been published and cannot be retrieved.
... (James Shaw, email to author, February 17, 2023).