An adverb meaning 'perhaps' or 'possibly', often used to indicate a less likely possibility (similar to 'maybe' or 'perhaps').
ひょっとしたら彼は来ないかもしれない。
He might not come, perhaps.
ひょっとしたら宝くじに当たるかもしれないよ。
You might possibly win the lottery.
ひょっとしたらそれが問題の原因かもしれない。
Perhaps that might be the cause of the problem.