White has a bishop aimed through the pawns on g6 and h7. On casual inspection the pawns seem to frustrate the bishop's hopes of accomplishing anything, but the appearance is deceiving. The bishop will pin the pawn on g6 if Black’s king can be brought to h7—and once that pawn is pinned, h5 becomes open for occupation. Here White makes use of this principle by connecting it with Lolli’s mate. He sees his pawn on f6 and so looks for the other elements of the pattern. He can get his queen to h6, which will start the pattern we saw in the previous frame. One more asset is needed: a heavy piece on the h-file to deliver mate at the end. White’s rook is ready; it can move to h5. Black guards the square with a pawn, but here's where the pinning idea comes in handy. Thus 1. Qh6, Rg8; 2. Qxh7+, KxQ (all familiar); and now Rh5# is made safe by the pin. It's checkmate because Black's king can't escape to g8 (his own rook now is there) or g7 (White seals it off with his pawn).

The point of the position is just to see the logic of the pattern. You might as well observe that mate can be delivered here by a different pattern as well: 1. Qh6, Rg8; 2. Rd8, anything; 3. Qg7#.