What does Exodus 16:23 mean?

He told them, 'This is what the Lord said: Tomorrow is a day of rest, a holy Sabbath for the Lord. Bake or boil what you need today, and save what’s left for tomorrow.' Exodus 16:23 - Modern Text Bible

(Moses explains that the extra is for the Sabbath, when they’re not supposed to gather food. They’re to prepare ahead and rest.)