וְאִתְּכֶ֣ם יִהְי֔וּ אִ֥ישׁ אִ֖ישׁ לַמַּטֶּ֑ה אִ֛ישׁ רֹ֥אשׁ לְבֵית־אֲבֹתָ֖יו הֽוּא׃
Associated with you shall be a representative from every tribe, each one the head of his ancestral house.
(The above rendering comes from the RJPS translation, an adaptation of the NJPS translation. Before accounting for this rendering, I will analyze the plain sense of the Hebrew term אִישׁ, by employing a situation-oriented construal as outlined in this introduction, pp. 11–16.)
This is one of 19 biblical instances where (singular, absolute) אִישׁ is repeated. While אִישׁ by itself has its own situating function, the repetition אִישׁ אִישׁ imparts a “no exceptions” meaning to the situation that is being depicted, as I explained at the first instance, Exodus 36:4; see my comment there.
One such type of usages, in which אִישׁ אִישׁ describes a thoroughgoing manner of distribution, is found not only in Exod 36:4, but also here and in Num 4:19, 49. In this case, participation in the census activity is distributed across the set of all tribes. The point of the repetition is that every single tribe must be represented—taking care not to leave out any of them. The reason for such care is not clear, but it seems to be a matter of equitable sacrifice—that is, full participation in the counting process will lead to fairness as to which men put their lives on the line in warfare.
As for the representation of each tribe, in his Anchor Bible commentary on this book, Baruch Levine writes persuasively at the next verse (1:5) as follows.
Prepositional lamed, as in lammaṭṭeh, functionally connotes representation and is a reflex of the possessive sense: “of each tribe; belonging to each tribe.” This is the function of prepositional lamed throughout the list of tribal leaders. Thus lirʾûbēn means “representing Reuben,” and so forth.
That connotation of representation is present with the ל already here in this verse.
As for rendering into English, when gender is not at issue, English idiom expects it to be specified only when it is not obvious to the reader. In this case, the mention of tribal leaders and a male pronoun (“each one the head of his ancestral house”) are more than enough evidence for the contemporary reader. Thus we have no warrant for rendering אִישׁ itself in gendered terms. The NJPS “a man from each tribe” comes across nowadays as unduly masculine. The revised rendering employs a gender-neutral noun. The claim is not that אִישׁ “means” representative per se (despite what I wrote in 2014 in my analysis of this verse for the URJ Press); rather, the Hebrew situating noun often evokes a type of situated participation that is best represented in English by a role term. In this case, given the preposition ל, the closest role is that of “representative.”
Finally, the NJPS rendering does not express the emphatic, across-the-board nature of the claim that is conveyed by the phrase אִישׁ אִישׁ. The revised rendering replaces each with every for this reason.