Predictors are variables that can be included in your data file/study to provide additional information to explain/predict the outcome. They can either be continuous numeric predictors or predictors with two distinct categories. SAT scores are always included as predictors in ACES completion studies, and you can also choose to include HSGPA and college GPA as predictors in your completion study (both supplied by your institution).
A completion study can have up to five additional predictors above SAT scores and the optional HSGPA and college GPA. An example of a predictor that an institution may choose to additionally provide is student credit load.