This is the second song in Green Day’s history where Billie Joe showed off his harmonica playing abilities (the 1st being Walking Alone, on Nimrod).

Hold On is a very straightforward song and you only need to know the G, C, D and Em chords to play it. However, the chord pattern isn’t very predictable so you might need to play it a few times to really get it down. Especially if you have a harmonica in your mouth at the same time.

Standard E tuning.

Green Day - Hold On chords and lyrics chart