The Vietnamese word "hẳn" is an adverb that is used to express certainty, assurance, or completeness in a statement. It conveys the idea of something being definite or without doubt.
Anh ấy hẳn sẽ đến.
(He will surely come.)
Cô ấy hẳn rất vui.
(She is certainly very happy.)
Tôi đi hẳn.
(I am going for good.)
In summary, "hẳn" is a versatile adverb in Vietnamese that emphasizes certainty and completeness. It is used to reinforce statements and can be combined with other words for specific meanings.