noun
Counts occurrences or repetitions of an action or event. Used with verbs to indicate frequency.
この薬は一日に三回飲んでください。
Please take this medicine three times a day.
彼は三回も同じ間違いをした。
He made the same mistake three times.
Means 'once' or 'one time'. 三回 is specifically 'three times'.
Means 'twice' or 'two times'. 三回 is one more repetition.
Compound of 三 (san, 'three') and 回 (kai, counter for occurrences).