Q: What does second position (cross harp) mean?

A: When you are playing second position (or cross harp), the key of the harmonica you are using is a fifth above (or a quart below) the key of the band. If the band is playing in E, for example, your harmonica will be in A. This situation allows you to play along very well with blues chord progressions using the lower draw notes of your harmonica. Actually this is only a useful notion on a diatonic harmonica. In that case the 2 draw will be the tonic of the song -- BB.