They saw him afar off: They refers to Joseph’s brothers. The brothers recognize Joseph because of his distinguished robe. We may say, for example, “They saw Joseph coming in the distance” or “They recognized Joseph while he was still far off.”

They conspired against him to kill him: conspired means “plotted” or “made plans.” The plan they made was to kill him (Joseph).

Quoted with permission from Reyburn, William D. and Fry, Euan McG. A Handbook on Genesis. (UBS Helps for Translators). New York: UBS, 1997. For this and other handbooks for translators see here .