It offers two features.
1. Calculations based on max liftsThe lifts of the calculator are.
Clean and Jerk
Pull (clean pull or deadlift?)
You enter your max for one specific lift and it calculates what your maxes for other lifts should/could/might be.
2. Your standings.
It will calculate your percentage of the current world record for your weightclass. It also gives you your sinclair scoring and Sinclair-Malone-Meltzer scoring (gives age bonuses for older people).
He gets no age bonus - if he would be born e.g. 1980 he would. And he also Snatches more than the calculator thinks he could. Same probably applies for the strength related numbers (squats).