the top; the best
Counter used to rank the top performers or items in a list, often in contexts like 'top 10' or 'best 3'. Commonly seen in rankings and competitions.
彼は大会でベスト3傑に入った。
He made it into the top 3 at the tournament.
この曲は今週のトップ10傑に選ばれた。
This song was selected for this week's top 10.
位 is the general counter for ranking any position (1位, 2位, etc.), while 傑 specifically marks someone or something as among the top/best in a set, as in 十傑 (the top ten).
From the kanji 傑, meaning 'excellence' or 'outstanding'. The counter usage likely developed from the idea of selecting outstanding items.