I need to block my opponent's immediate winning threat. They have two Xs in positions (1,0) and (1,1) of the middle row. If I don't place my O at position (1,2), they will win on their next move by completing that row. This is a defensive move that prevents an immediate loss. Additionally, after blocking this threat, I can start working on creating my own winning opportunity with my O already at the top-left position.