Modalities are tools or therapies one can utilize to improve recovery. Any modality that increases blood flow to fatigued muscles may help speed the recovery process by removing exercise byproducts and delivering nutrients to the muscle. My personal favorites are hot therapies and light workouts like recovery sessions or hiking.
Reference: Sands, W. A. (2016). Chapter 18: Thinking sensibly about recovery. Strength and Conditioning for Sports Performance, 451-475. New York, NY: Routledge.