A rank order list (ROL) is the list of programs you submit to the NRMP after interviews, ordered from most to least preferred. Programs submit their own list of applicants. The Match algorithm then places each applicant in the highest-ranked program on their list that also ranked them and has an open position.
Because the algorithm favors the applicant's preferences, rank programs in your true order of preference, not where you think you are likely to get in. Only rank programs where you would be willing to train.