Ok all you Diner Dash experts. I have what probably is a dumb question

, but help me understand chaining. I thought that Flo can only do two of the same things at once; i.e. take two checks to the counter, serve two tables at a time, etc. SO, WHAT EXACTLY IS CHAINING??? I'm stuck on the second restaurant at (I think) level 7 or 8 (the one with all the business women). Thanks!