You and the people with you is literally “both you and these people who [are] with you.” This refers to Moses and the people coming to him for advice. So Contemporary English Version has “You and the people who come to you.” Will wear themselves out is emphatic, literally “withering, you [singular] will wither.” This form emphasizes the basic meaning of the verb, so New Revised Standard Version has “You will surely wear yourself out, both you and these people with you.”

For the thing is too heavy for you is literally “for heavy from you the davar [thing, deed].” Some translations have “task” for davar (Revised English Bible, New American Bible, New Jewish Publication Society’s Tanakh), while others have “work” (New International Version, New Jerusalem Bible). You are not able to perform it alone is literally “you [singular] are not able to make it by yourself.” New Jewish Publication Society’s Tanakh and others have “You cannot do it alone.” Good News Translation combines the two clauses into one: “This is too much for you to do alone.” One may also say “You cannot judge all these cases alone.”

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 .