The Apple HFS file system family can deal with filenames in
native language character sets. These character sets are stored in
so-called MAC codepages. You need to include the appropriate
codepage if you want to be able to read/write these filenames on
Mac partitions correctly. This does apply to the filenames
only, not to the file contents. You can include several codepages;
say Y here if you want to include the Mac codepage that is used for
Cyrillic.

If unsure, say Y.