Ephesus is the city in modern day Turkey where John is thought to have written his Gospel, and where Paul spent a few years. The inhabitants at the time were Greek ethnically. Paul does not give characteristically personal greetings in this letter, suggesting to some that he did not write this in 62 AD from Rome, but it was written in his name between 80 and 100 AD.
The first chapter has a greeting, writes of redemption in Christ and then is a prayer for spiritual wisdom. This verse is from the prayer. It is said that to understand the bible, one needs to be a believer.