This is the 3963rd most frequent Japanese word.
ス
The Japanese katakana character "ス" represents the sound "su."
ス is part of 'テニス' which means Tennis, showing it as part of a loanword.
私は明日テニスをします。
I will play tennis tomorrow.
スッ is an onomatopoeic expression indicating a smooth or swift action.
彼がスッと立ち上がった。
He stood up swiftly.
ス exists in both 'スプーン' (spoon) and 'スープ' (soup), indicating its use in loanwords.