This is the 6165th most frequent Arabic word.
يصح
"يصح" means "to be correct" or "to be valid."
In this sentence, 'يصح' indicates the state of recovery or improvement in health.
يصحُ الطفل بعد تناوله الدواء.
The child recovers after taking the medicine.
Here, 'لا يصح' reflects the notion of something being incorrect or inappropriate.
لا يصحُ أن تتحدث بهذا الأسلوب مع الأكبر منك.
It is inappropriate to speak in this manner with someone older than you.
In this usage, 'يصح' denotes the possibility of correctness or appropriateness.