# He had eight sons

"He" refers to Jesse.

# Jesse was an old man ... very old among men

The two phrases mean basically the same thing and are combined for emphasis. (See: [[rc://en/ta/man/translate/figs-parallelism]])

# second to him Abinadab, and the third Shammah

"Abinadab the second born, and Shammah the third born." This phrase shows birth order.