who slept with her
It is implied that Jacob did not know he was with Leah because it was dark and he could not see. The full meaning of this statement can be made explicit. (See: rc://en/ta/man/translate/figs-explicit)
Laban gave his female servant Zilpah ... her servant
Here the author gives background information about Laban giving Zilpah to Leah. Most likely he gave Zilpah to Leah before the wedding. (See: rc://en/ta/man/translate/writing-background)
This is the name of Leah's female servant. (See: rc://en/ta/man/translate/translate-names)
behold, it was Leah
"Jacob was surprised to see it was Leah in bed with him." The word "behold" here shows that Jacob was surprised by what he saw.
What is this you have done to me?
Jacob uses a question to express his anger and surprise. This rhetorical question can be translated as a statement. AT: "I cannot believe you did this to me!" (See: rc://en/ta/man/translate/figs-rquestion)
Did I not serve you for Rachel?
Jacob uses these questions to express his hurt that Laban had tricked him. This rhetorical question can be translated as a statement. AT: "I served you for seven years to marry Rachel!" (See: rc://en/ta/man/translate/figs-rquestion)