The equation H = (ℓ - b/sinθ) describes the relationship between the length of the rope (ℓ) and the diagonal stretch of the rope (b/sinθ) in a frictionless pulley system. The diagonal stretch is crucial for understanding how the rope behaves under tension. The discussion also highlights the successful application of TikZ for creating diagrams, indicating progress in visual representation of mathematical concepts. Additionally, the user shares their experience of improving their LaTeX skills through creating more diagrams. Overall, the conversation emphasizes the importance of visual aids in understanding pulley mechanics.