Guitar bar chords (or barre chords/barré chords) play an important part in guitar playing. They are used extensively in all kinds of music.
Bar chords are called the way they are because you 'bar' all the strings at one fret with your index finger. When doing this your finger replaces the nut of the guitar. Taking all the frets with one finger is not an easy thing to do. I wish I could offer you a bar chords made easy solution, but I'm afraid I can't. You have to give this some time and practice. I've had a few students who could fret guitar bar chords almost perfectly within first week they started learning them, but for most beginning guitar players it takes a bit longer. Once you're able to play them you wonder what was so difficult about it (but I guess that's the case with most of the things you learn).