"Photoshop Brushes" are vectorial shapes that can be used as painting tools in the creative software. It could be described as "digital stamps". The generic ones provided by Adobe are mostly basic or kitch.
Steambot Studios have been creating their own brushes for more than 5 years now to accelerate their speed paintings process. They design, program, and gather them into thematic packs.
You can get it and every other Brushes packs on Steambot online store.