Fretboard charts have one "line" for each string on the bass, and as you progress from left to right down that line, you'll see the note that is created when you pluck the string while pressing each string to a particular fret.
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Although most beginners start with the standard four string bass, if you happen to have a five or six string bass, remember you'll need a fretboard chart that covers that kind of instrument.
Now that you know what a fretboard chart for a bass guitar is, as well as where to find one and how to use it, it's time to get one for yourself and get to work!
The most important thing to become familiar with is the shape of these chords, as the shapes will remain similar no matter where you play them on the fretboard.