A pair: two items or people grouped together as a set; a duo or matched set.
この靴はペアで販売されています。
These shoes are sold as a pair.
会場はペアで申し込みが多かった。
There were many registrations for pairs at the venue.
友達とペアでプレゼントを選んだ。
I chose a present in a pair with my friend.
A pair-oared boat in rowing: a boat class with two rowers (one oar each).
オリンピックにはシングルやペアなど複数の種目がある。
The Olympics include several rowing events such as singles and pairs.
彼らはペアで出場して銀メダルを獲った。
They competed as a pair and won the silver medal.
In card games (especially poker), a 'pair' is a hand containing two cards of the same rank.
彼はポーカーでワンペアを作って勝った。
He made a pair in poker and won.
この手札はペア二つ（ツーペア）なので強い方だ。
This hand has two pairs, so it's relatively strong.