This is one of the titles of a church official who oversees a local congregation of Christ's church in the company of fellow bishops (always a plurality of men).
"Bishop" translates the Greek term episcopos, literally "oversee." The bishop is the same as an elder (presbuteros -- older man; see Acts 20:17; 28). He is also identified as a "shepherd" or "pastor" (poimen -- one who tends, feeds, and protects; cf. Eph. 4:11).
Peter uses forms of all three of these terms in 1 Peter 5:1-2 when he instructs the elders to tend the flock among them, within which they exercise the oversight (cf. Heb. 13:17).
The qualifications of these officers are found mainly in 1 Timothy 3 and Titus 1. The notion that a bishop is over a large area of the church (as in the teaching of Catholicism) is foreign to the Scriptures.