A B7 chord contains the notes B, D#, A, F#. It is built from the dominant 7th formula 1 - 3 - 5 - ♭7, with B as the root.
Is B7 easier than B major?
Often, yes. Unlike B major, the common B7 voicing doesn't require a full barre — it uses four separate fingers across the middle strings. Many players learn B7 first and come back to B major once barre technique is stronger.