Amitabha is the celestial Buddha of Infinite light.
On this representation, he exhibits Samadhi Mudra his two palms folded face up, one on top of the other, lying on his lap, and many sign of his royal rank.
According to the Larger Sutra of Immeasurable Life Amitabha was, in very ancient times and possibly in another realm, a monk named Dharmakara, and/or in some versions of the sutra a former king who, having come into contact with the Buddhist teachings through the buddha Lokesvararaja, renounced his throne.
He then resolved to become a buddha and so to come into possession of a buddhaksetra ("buddha-field", a realm existing in the primordial universe outside of space time, produced by a buddha's merit) expressed resolutions in forty-eight vows.
In the versions of the sutra widely known in China, Vietnam, Korea and Japan, the eighteenth vow was that any being in any universe desiring to be born into Amitabha's Pure Land and calling upon his name even as few as ten times will be guaranteed rebirth there.