Hinami challenged Tsukino to a yugioh duel (duel is the term the franchise uses to refer to matches)
But Tsukino interpreted it as a literal physical fight and beat Hinami up.
The 5 cards Hinami dropped form an instant win condition in yugioh (the most well known and iconic one too), meaning Hinami would literally win right out of the gate, had Tsukino not beat her up.
Basically Hinami's plan was to start a yugioh duel, immediately reveal the 5 cards (the 5 pieces of exodia the forbidden one) and win instantly.