The swastika used in Buddhist art and scripture is known as a manji (Japanese; whirlwind), and represents Dharma, universal harmony, and the balance of opposites. In China, it is called wan.
It is derived from the Hindu religious swastika, but it is not identical in meaning. The Manji is made up of several elements: a vertical axis representing the joining of heaven and earth, a horizontal axis representing the connection of yin and yang, and the four arms, representing movement- the whirling force created by the interaction of these elements.
When facing left, it is the Omote (front facing) Manji, representing love and mercy. Facing right, it represents strength and intelligence, and is called the Ura (rear facing) Manji. In Zen Buddhism, the Manji represents an ideal harmony between love and intellect.