What is a file whose name starts with ._ prefix?
macOS creates files whose names start with a dot and underscore (._) to store information about other files. These files with the prefix to their names are created only in some file systems developed not by Apple, including the FAT and exFAT. macOS considers the files as a kind of system files and makes them invisible to its user, but you still can view the files on Windows.
For example, after copying a file to a USB drive in the exFAT format...
