If you want to know how Ameria's Strength matches to the other Stars, Just follow the chart to find her strength (as in red above). The number to the right of that (underlined in green above) tells you the rating of that stat.
In this case, her STR is ranked 5. That means that her STR are about average. If the number were 1, that would mean that she had the highest strength. If the number in green were a 10, that would mean that she had the lowest strength.
If you want to add to a certain stat, there is a chart at the bottom that tells you which equipment sets will add to which stat and how much.
Keep in mind that the numbers listed there are for the entire set, but doesn't include the bonus amount. It will however tell you if there is a bonus for that stat.
Want to know more about getting your characters to level 99?
Note: A (+) beside a stat means that there is a bonus added with that set for that stat. The amount varies.