Chord Shapes would basically refer to the arrangement of your fingers on the fretboard that you use to get the notes you need. Usually a chord has more shapes than one. It depends on personal preference but gradually you get used to (and prefer) one chord shape than another for a particular chord.
Shapes affect the tonality of the chord as well. Try out different shapes for each chord (use a chord book) and see which suits you. You may have to use a different shape for playing chords to get the feel of some songs right (depends upon the songs).
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