This rhetorical question can be translated as a positive statement. Alternate translation: "The whole land is available for you to use." (See: [[rc://en/ta/man/translate/figs-rquestion]])
Possible meanings are 1) "If you go one way, then I will go the other" or 2) "If you go to the north, I will go to the south." Abram let Lot choose the part of the land he wanted, and Abram would take what remained.