The phrase "proper form" means doing something correctly and in the right way, following the rules or guidelines for how it's supposed to be done. Full definition
If you fail to perform 5 reps with proper form with a given weight, you will use the same weight for the next workout. (fitnessandpower.com)
Remember to keep proper form of spinal alignment, don't lock your joints, and work with your range of motion throughout the exercises. (agymrat.com)
Make sure to focus on maintaining proper form on every rep of every exercise and opt for three workouts per week for optimal results. (fitnessandpower.com)