Jesus uses a second question explain how the disciples would actually treat a servant. This can be a statement. Alternate translation: "He will certainly say to him ... eat and drink'" (See: [[rc://en/ta/man/translate/figs-rquestion]])
"tie your clothes at your waist and serve me" or "dress up properly and take care of me." People would tie their clothes closely around their waist so that their clothes would not get in their way while they worked. (See: [[rc://en/ta/man/translate/figs-explicit]])