For every Sus2 chord you'll come across, there will probably be a Sus4 chord not far away! As you may have guessed by the name, this is another suspended chord, except this time we use the fourth note of the scale, rather than the second.
As with all chords, we simply need to learn the formula to be able to build the chord. In the case of Sus4 chords, we are talking about suspended 4th chords. Suspended simply means that you take the 3rd note from a chord, suspend it (remove it) and replace it with a 4th note instead. Therefore, you get the formula 1st, 4th & 5th from the major scale. Here is an example: