1500: SAT Score of 1500 (of 1600, puts them in the 99%-ile)

4.0+: 4.0+ Grade Point Average (D=1 grade point A=4, Advanced Placement courses [AP] are +1 on the grade point so you can be over 4.0 on a 4 point scale.)

12+ AP: is they've taken 12 or more Advanced Placement courses, which are in theory equal in rigor and difficulty to college level courses.

Basically means they spent their entire high school taking as many of the hardest classes they can, and earning an A in all courses.

1500 (out of 1600) on the SAT, 4.0 out of 4.0 grade point average (GPA), took 12 Advanced Placement (AP) courses, akin to foundational college-level courses, while in high school. Generally just getting the highest possible marks on every typical academic metric.