Knowing mating patterns lets you see mate quickly in a game. The first: the queen supported by the king. The black king is on the edge; mate with the queen, but Qh6 is stalemate!
Other patterns: back-rank mate (rook or queen on the eighth rank), ladder mate (two heavy pieces), smothered mate (knight), Arabian mate (rook and knight). In the next lesson you'll see the rook-and-knight mates.