You are spies
Spies are people who secretly try to get information about a country to help another country.
You have come to see the undefended parts of the land
The full meaning can be stated explicitly. AT: "You have come to find out where we are not guarding our land so that you can attack us" (See: rc://en/ta/man/translate/figs-explicit)
This is a way to refer to someone to honor them.
Your servants have
The brothers refer to themselves as "your servants." This is a formal way of speaking to someone with greater authority. AT: "We, your servants, have" or "We have" (See: rc://en/ta/man/translate/figs-123person)