Lesson
White to move. Main line: 1. Bb5+ Kd8 2. Bxd7
1.Bb5+ opens the e-file for the rook and places the bishop on a diagonal to the queen on d7. The plus sign belongs to the rook, not the bishop.
Black has to move the king. Only then does 2.Bxd7 take the queen, with no opportunity for Black to move it away in between.
A discovered check gives the moving piece a free action. Use that action to capture, fork or attack the most valuable target it can reach.