Meaning: A formal exclamation, often used in the Bible.
1 Kings 3:12
Behold, I have done according to thy words: lo, I have given thee a wise and an understanding heart; so that there was none like thee before thee, neither after thee shall any arise like unto thee.
Ezekiel 2:9
And when I looked, behold, an hand was sent unto me; and, lo, a roll of a book was therein;
Ezekiel 37:2
And caused me to pass by them round about: and, behold, there were very many in the open valley; and, lo, they were very dry.
Luke 17:21
Neither shall they say, Lo here! or, lo there! for, behold, the kingdom of God is within you.