John Gill Commentary 1 Chronicles 7:40

"All these were the children of Asher, heads of the fathers` houses, choice and mighty men of valor, chief of the princes. And the number of them reckoned by genealogy for service in war was twenty and six thousand men." — 1 Chronicles 7:40 (ASV)

All these were the children of Asher, heads of their father's
house
Principal men in their tribe, and respective families:

choice and mighty men of valour ;
these were some selected from others, being eminent for their courage and valour:

chief of the princes ;
or chief princes; the Vulgate Latin version is, dukes of dukes, they were heads of their fathers' families:

[and] the number throughout the genealogy that were apt to war, and to
battle, [was] twenty and six thousand [men] ;
that is, in the days of David, (1 Chronicles 7:4) , this was the number, not of their chief men, nor of all the people in the tribe, but of their militia.