This is the 2060th most frequent Chinese word.
从不
"从不" means "never."
In this sentence, '从不' is used as an adverb to emphasize that the subject, 'he', consistently maintains the habit of never being late.
他从不迟到。
He is never late.
Here, '从不' indicates that the subject, 'she', habitually refrains from complaining about others, showing an ongoing characteristic.
她从不抱怨别人。
She never complains about others.
Here, '从不' illustrates a persistent and ongoing refusal to abandon hope in any situation.