The Buddha’s hand, held close to his heart with thumb and forefinger tips touching symbolizes the transmission of the knowledge he has gained after attaining enlightenment. Another name for this gesture is Vyakhyana Mudra or the “mudra of instruction”. The circle formed by the fingers touching each other signifies perfection, with no beginning or end, like the law of Dharma itself.
There are many variations. The Buddha may be seated or standing while gesturing thus. In other poses, both his hands may display the Vitarka Mudra.