A teaching unit is 45 minutes, and that is the unit every rule here is written in. The bars are the legal or published range each route can charge you. Set your level and your situation and the ranges move.
Ranges come from the Berlin fee rules for the Volkshochschulen, the federal integration-course contribution, the job-related German-course contribution, and two published Berlin school price lists. Schools set their own prices inside those rules, so treat the bars as the frame, not a quote.