# Lord

This is a title of respect. Possible meanings are 1) Abraham knew that one of these men was God or 2) Abraham knew that these men came on behalf of God.

# if I have found favor in your sight

"if you have evaluated me and approve" or "if you are pleased with me" 

# in your sight

Abraham is speaking to one of the men.

# do not pass by

"please do not keep on going past"

# your servant

"me." Abraham refers to himself this way in order to show respect to his guest.