This is the 1790th most frequent Japanese word.
助
"助" means "help" or "assist."
In this context, '助' is used in the verb '助ける' meaning 'to help', forming an imperative with politeness.
助けてください！
Please help me!
Here, '助' is used in the same verb '助ける', in its past tense form '助けて' to indicate an action completed in the past.
彼は困った時に私を助けてくれました。
He helped me when I was in trouble.
In this sentence, '助' is part of the verb '助かる', meaning 'to be of help or saved', which is in its polite form to express appreciation.