This is the 5866th most frequent Japanese word.
ぺし
"ぺし" is an onomatopoeia that represents the sound or action of light slapping or striking something.
ぺし is used here to express the sound or action of a light smack or hit.
彼は頭をぺしっと叩いた。
He lightly smacked his head.
In this sentence, ぺしぺし conveys the repetitive tapping sound or action.
ぺしぺしと壁を叩いて音を確認した。
He tapped repeatedly on the wall to check the sound.
Here, ぺしっ represents a brisk or sharp style of action.