Just before Faustus says these lines, the Good Angel and the Evil Angel have been with him, attempting to convince him to make the choice they prefer. They leave him, with the Evil Angel having the last word and encouraging him to "Think of honor and of wealth."
When the angels leave, Faustus does start thinking about how much better his life will be if he accepts the deal with the devil and gains wealth from it. The "signiory of Emden" were respected and well-to-do men from the town of Emden, which was an important business center during the period of time when Doctor Faustus was written.
Faustus is looking forward to becoming as respected and important as those gentlemen, realizing that no god or human could harm him when he has the protection Mephastophilis would provide after signing his deal with Lucifer, the devil.
"Veni" is the Latin word for "come" - ironically, Faustus is using the language of the Roman Catholic Church to call for the return of the devil's representative.