What does 1 Chronicles 25:19 mean?

the ninth to Mattaniah, his sons and his brothers, twelve;

the tenth to Shimei, his sons and his brothers, twelve;

the eleventh to Azarel, his sons and his brothers, twelve;

for the thirteenth, Shubael, his sons and his brothers, twelve;

for the fourteenth, Mattithiah, his sons and his brothers, twelve;

for the fifteenth to Jeremoth, his sons and his brothers, twelve;