When going to class, if possible, perform this prior to class.
When you see 5+, 3+, or 1+, that means you do the max reps you can manage with that weight, with the goal of setting a rep record in each workout. Yet with good form. Don't let the ego do the lifting, you will get hurt.

Week 1 workout for bench press. Using the example above, if your 1RM is 100kg, you calculate all your percentages from 90% of that max, or 90kg.
So you're using 58.5kg (65% of 90) x 5, 67.5kg x 5, and 76.5kg x 5 or more unbroken set. Rest 90s. to 2 min.

75% x 5
85% x 3
95% x 1+