With the pawn on the seventh the defender relies on perpetual check. The attacker's main weapons are cross-checks: answering a check with a check that also forces a queen trade or shields the king.
Queen and pawn versus queen is one of the hardest practical endings, but a pawn on the seventh with a sheltered king is usually a win. Black has just checked from f3 along the long diagonal, and White's king on b7 is in check. The natural reactions are to run with the king; the strong reaction is the cross-check.