"One evening Isaac went out to the field to think." This must have been a long time after the servant and Rebekah left her home since they had to travel a long distance.
The word “behold” here alerts us to pay attention to the surprising information that follows. This could be translated as "When he looked up he was surprised to see camels coming."
## Rebekah looked ##
"Rebekah looked up"
## she jumped down from the camel ##
"she quickly got off the camel"
## So she took her veil, and covered herself ##
"So she covered her face with her veil."
## veil ##
a piece of cloth used to cover a person's head, shoulders, and face