A barre chord is where the guitarist forms a bar across all 6 or 5 strings of the fretboard emulating the nut on the fretboard. It is effectively a movable open string chord. It allows the player to move an open chord up and down the neck. The technique opens up a whole world of tonal possibilities. Chord charts are graphical reparations of how to make a chord.

Barre chords are often very challenging for anyone learning to play the guitar. What about big fingers, does that hinder playing barre chords? No it does not.