וְעָנ֣וּ הַלְוִיִּ֗ם וְאָ֥מְר֛וּ אֶל־כׇּל־אִ֥ישׁ יִשְׂרָאֵ֖ל ק֥וֹל רָֽם׃
The Levites shall then proclaim in a loud voice to the entire body of Israel:
(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.)
On the meaning of the definite noun phrase כֹּל אִישׁ יִשְׂרָאֵל here, see my comment at 29:9.
In short, the referring expression כֹּל אִישׁ יִשְׂרָאֵל functions to collectively denote the Israelite leadership, while situating the people Israel in its covenant with God, prior to a rite that formalizes that covenant.
As for the translation, the NJPS “all the people of Israel” is unlikely, as explained at 29:9. The revised rendering reflects a situating approach, expressed in English idiom.