Definition - What does Yang mean?
Yang is a part of the Taoist concept of the balanced and harmonized energies in nature, with the other part being it's opposite: yin. The characteristics of yang include rapid, energetic, male, assertive, light, obvious, heavenly and external. Yogis may wish to practice Yin/Yang yoga in order to harness or display these particular qualities found in yang’s energy.
Yogapedia explains Yang
In Taoist philosophy, Yin/Yang is the idea that the two energies found in nature come together to form a balanced whole. This concept is mirrored in the opposites of night and day, male and female, and water and fire.
Yin/Yang yoga seeks to cultivate or display the characteristics of these energies. Yin/Yang yoga is based on principles from both India's Hatha yoga and China's Taoist philosophy and practice. It was established in the Western parts of the world by Paulie Zink in the 1970s.
When Yin/Yang yoga is practiced by incorporating the two energies, it begins with a slow-paced and meditative form of yoga that speeds up with more energetic asanas incorporated throughout the practice. Yin/Yang yoga practitioners seek to nurture balance within and interconnectivity of the self with all things, hence a practice that incorporates both yin (slow, meditative) and yang (energetic, external).