en_tn_lite_do_not_use/num/26/05.md

General Information:

The leaders of Israel are counting the men, 20 years old and older, according to their tribes and families. (See: rc://en/ta/man/jit/translate-names and rc://en/ta/man/jit/translate-numbers)

was the firstborn of Israel

Here "Israel" refers to the man also known as Jacob.

From his son

The word "his" refers to Rueben.