שִׁשָּׁה֙ מִשְּׁמֹתָ֔ם עַ֖ל הָאֶ֣בֶן הָאֶחָ֑ת וְאֶת־שְׁמ֞וֹת הַשִּׁשָּׁ֧ה הַנּוֹתָרִ֛ים עַל־הָאֶ֥בֶן הַשֵּׁנִ֖ית כְּתוֹלְדֹתָֽם׃
six of their names on the one stone, and the names of the six that remain on the other stone, according to their birth.
Read kabbalistic (mystical) interpretation of Exodus 28:10: and classical mystical sources.