Genesis: "origin" (Hebrew: Bereshit - "In the beginning")
Exodus: "going out" (Hebrew: Shemot - "Names")
Leviticus: "relating to the Levites" (Hebrew: Vayikra, - "And he called")
Numbers: numbering of the Israelites (Hebrew: Ba Midbar - "In the desert")
Deuteronomy: "second law" (Hebrew: D'varim - "Words")
Hope that helps! :)