لَوْ وُزِنَتْ ... لَوَزَنَتْهُنَّ
If they were weighed, they would outweigh or match what had been recited.
لَوْ introduces a hypothetical condition. وُزِنَتْ is passive (“were weighed”), and the later clause expresses the result.
ثَلَاثَ مَرَّاتٍ means “three times”; مَرَّات is the plural of مَرَّة.
The expression points to the remarkable value of remembrance, not a dismissal of sustained worship.