Karesansui, Sanzenseki Group

Quick answer：

Karesansui, or 'dry landscape' in Japanese, is a form of Japanese garden that uses carefully raked sand and rocks to represent water and mountains. The Sanzenseki Group refers to a set of three rocks often found in such gardens, symbolizing the peak of a mountain. These gardens are designed to evoke a sense of tranquility and the beauty of nature, and are an important part of Zen Buddhism.