Lehi means literally "a jawbone". The first mention of the name Lehi refers to a place in the tribe of Judah where Samson achieved a victory over the Philistines (Judg. 15:9, 14, 16), slaying a thousand of them with the jawbone of an ass. The words in 15:19, "a hollow place that was in the jaw" (A.V.), should be, as in Revised Version, "the hollow place that is in Lehi." (Source: Easton's 1897 Bible Dictionary )
Lehi was a prophet living in Jerusalem around 600 BC. He is a contemporary of the biblical prophet Jeremiah. Lehi, as well as Jeremiah, both prophecied that Jerusalem would be destroyed if the people didn't repent. As a result, his life was threatened.
Book of Mormon Account
According to the "First Book of Nephi", Lehi recieved a revelation that he was to leave with his family to avoid the imminent destruction of Jerusalem around 600 BC. Being obedient, Lehi left with his wife, Sariah, and his sons, Laman, Lemuel, Sam. While in the wilderness, Jacob and Joseph were born. Lehi and his family eventually travelled to the Americas via boat constructed by his son, Nephi.
While in the wilderness, Lehi had a dream about a "great and spacious building", and a "rod of iron." The great and spacious building represented the pride of the world, while the rod of iron represented the word of God. Lehi, Sariah, Nephi, and Sam all held to the iron rod, and partook of the fruit which was "exceedingly delicious about all other fruit" representing the love of God.
However, Laman and Lemuel, did not follow the rod, and entered the great and spacious building. Lehi related this dream to his family, and asked Laman and Lemuel to reconsider their ways and follow God. However, even with all the promptings, the two older brothers resisted, and ended up fulfilling the dream, becoming enemies to their brothers.
Also in the wilderness, Lehi found the Liahona, a round ball that functioned similar to a compass. However, it only worked as the family was righteous, directing them where they should travel. When they did not follow God, the Liahona failed to work.
Lehi and Sariah both travelled to the americas. Soon after their arrival, both parents died. At their death, there was a struggle over who should lead the families. Nephi was directed in a dream to leave with those who would follow him, and the groups eventually separated into the Nephites and Lamanites.