This is the Hebrew word for "man". It could be ultimately derived from Hebrew אדם ('adam) meaning "to be red", referring to the ruddy colour of human skin, or from Akkadian adamu meaning "to make".
According to Genesis in the Old Testament Adam was created from the earth by God (there is a word play on Hebrew אֲדָמָה ('adamah) "earth"). He and Eve were supposedly the first humans, living happily in the Garden of Eden until they ate the forbidden fruit from the tree of knowledge. As a result they were expelled from Eden to the lands to the east, where they gave birth the second generation, including Cain, Abel and Seth.
As an English Christian name, Adam has been common since the Middle Ages, and it received a boost after the Protestant Reformation. A famous bearer was Scottish economist Adam Smith (1723-1790).