Learning to play the guitar involves learning to play chords on the guitar. How many chords should you learn? As much as you need to achieve your goals. Usually, the more you play, the more you'll want to learn. I usually recommend you start out with the beginner guitar chords, and work your way up from there.
Once you start playing songs, you'll need to learn a whole bunch of chords anyways, it's all part of the learning process. This is why we created our free guitar chords library, containing the chord chart and fingering to over 1,000 chords. Now will you need to memorize all of those chords? No way! But the chord library provides a great reference for you, when you don't know the fingering to a chord, looking for the intervals of a chord, or the you need to play to arpeggiate it.