I need to block the opponent's potential win in the left column where they already have O at (0,0) and (2,0). If I don't place my X at (1,0), they could win on their next move. Additionally, this move sets up a potential win for me in the middle row - after placing at (1,0), I would have X at (1,0) and (1,1), and could win by placing at (1,2) in a future move if given the opportunity.