They refers to “The Egyptians,” or simply “people.” Did not see one another is literally “a man did not see his brother.” It uses the simple indicative form of the verb, but the context suggests that they were not able, or “could not see each other” (Good News Translation). The word for “brother” may also be understood as “neighbor” (Durham). So one may translate “The Egyptians could not even see the person living nearby.” However, in most languages something like “The Egyptians could not see each other” will be a natural translation. Nor did any means “and no one” (Good News Translation). Rise from his place is literally “rise from beneath him.” It is idiomatic for “get up from where he was” (New Jewish Publication Society’s Tanakh). New Revised Standard Version (and others) have “could not move from where they were,” probably referring to their houses. So Good News Translation has “and no one left his house during that time.” Contemporary English Version has “During that time” at the beginning of the verse and translates as “During that time, the Egyptians could not see each other or leave their homes.” This will be a good model in a number of languages. For three days corresponds to the “three days” of “thick darkness” in verse 22. But note that it may be expressed simply as “during that time” (Good News Translation).

But all the people of Israel again excludes the Israelites from the effects of the plague upon the Egyptians (as in 8.22; 9.4, 7; and 9.26). Had light where they dwelt here refers primarily to daylight, something difficult to imagine unless where they dwelt refers to “the land of Goshen” (8.22). Good News Translation therefore translates “But the Israelites had light where they were living,” and Contemporary English Version has “but there was light where the Israelites lived.” But the Hebrew uses the plural form, “dwellings” (New Jewish Publication Society’s Tanakh), and there is no other clue here suggesting that the Israelites were living separately from the Egyptians. The very opposite is suggested in 11.2 and elsewhere. Therefore in translating this verse one should not suggest either that the light for the Israelites was an artificial light or that the Israelites were living in a separate region.

Quoted with permission from Osborn, Noel D. and Hatton, Howard A. A Handbook on Exodus. (UBS Helps for Translators). New York: UBS, 1999. For this and other handbooks for translators see here .