It's a common catchphrase used by Naruto Uzumaki, and it's generally understood to be an exclamation that adds emphasis to his statements. While it doesn't have a strict definition, it's often interpreted as conveying a mix of:
* Determination: It's often used when Naruto is determined to achieve something, or to express his confidence.
* Optimism: Naruto is known for his positive outlook, and "Dattebayo" reflects this.
* Childishness: It's a somewhat childish phrase, which fits Naruto's personality, especially in the early parts of the series.
However, the meaning of "Dattebayo" is ultimately up to individual interpretation. It's part of Naruto's unique charm and personality, and it adds a layer of humor and relatability to his character.