Many pop songs are written in C Major Scale. When you know how to play these basic chords and progressions it becomes a lot easier to recognize them in songs !

It is common to number the chords, starting with the I (roman 1) for the first chord in the scale.

For C major, the I chord is obviously C major.

A chord progression that is seen in a lot of pop and blues songs is I-IV-V

In the scale of see this would be:

I: C Major

IV: F Major

V: G Major

Have a go at playing these chords and it will probably immediately sound familiar ! :)