Following is a brief explanation of the verse: “na, bhikkhave, buddhavacanaṃ chandaso āropetabbaṃ. Yo āropeyya, āpatti dukkaṭassa. Anujānāmi, bhikkhave, sakāya niruttiyā buddhavacanaṃ pariyāpuṇitun”ti”
chandaso = (convert to) Sanskrit verse, āropetabbaṃ = I declare (as a Vinaya rule)
Yo āropeyya = whoever breaks that (Vinaya rule), āpatti dukkaṭassa = will be subjected to suffering
Anujānāmi = I give permission, sakāya niruttiyā buddhavacanaṃ = to provide meanings of Buddha Vacana (Buddha Dhamma) in one’s own dialect
pariyāpuṇitun = should learn well.
Therefore, the whole sentence can be translated as: “Bhikkhus, I declare that Buddha Dhamma should not be converted to Sanskrit verse (chandaso). Whoever breaks that Vinaya rule will be subjected to suffering. I give permission to express the meanings (nirutti) of Buddha Dhamma in one’s own dialect, to learn it well.”
The word “chandaso” as “Sanskrit verse” is stated in the following Wikipedia article too: “Sanskrit prosody”
From that article: “Sanskrit prosody or Chandas refers to one of the six Vedangas, or limbs of Vedic studies . It is the study of poetic metres and verse in Sanskrit . This field of study was central to the composition of the Vedas, the scriptural canons of Hinduism, so central that some later Hindu and Buddhist texts refer to the Vedas as Chandas [1,2].”