>To say that when a person tries to do something, it works out at the third attempt
>Uses to inspire someone for third attempt, when already failed twice
The phrase is associated with “Holy Trinity of Christianity” and this is to be believed that something that comes at number three always brings the fortune.
Example
The fellow finally managed to pass his exam. As they say, third time’s a charm
He married twice before this but now expects that third time will be a charm for him