。
She played cards with Roy.
Literal
[topic-は] Roy [with-と] cards [object-を] did.
トランプ in Japanese refers to playing cards in general — despite originating from English 'trump,' the meaning shifted in Japanese to mean any standard deck of 52 cards. This is a classic case of a borrowed word taking on a local meaning. ~をする ('to play, do') is the standard verb for playing games or card games (compare 野球をする 'play baseball,' 将棋をする 'play shogi'). The と is the comitative particle marking the partner.