The phrase "to use the scale" means to measure or compare something using a system of measurement, usually represented by numbers or a rating system. Full definition
They have a series of suggested questions, some of which use a scale of one to five. (schoolsweek.co.uk)
Don't use the scales as a judge of how much weight you have lost because by doing resistance training and increasing your muscle mass you may not see much difference. (fitbodyhq.com)
This is exactly why I talk about not using the scale as an indicator of your progress. (thebettyrocker.com)