Learn Farsi: شما باید نظم و نظافت را رعایت کنید.

After bāyad (must), the verb must be in the subjunctive mood. While the subjunctive usually takes a be- prefix, it is very common in modern Farsi to drop this prefix for compound verbs formed with kardan. You will hear re'āyat konid much more often than re'āyat bekonid.

Why does the direct object marker rā come after the entire phrase nazm va nezāfat?

When you have multiple direct objects joined by 'and' (va), they are treated as a single unit. The object marker rā attaches to the very end of that complete noun phrase, showing that you must observe both 'order' and 'cleanliness'.

How is the conjunction و pronounced in the middle of this phrase?

In everyday spoken Farsi, the conjunction va is almost always reduced to a short '-o' sound linking the two words. You will mostly hear native speakers say nazm-o nezāfat.

Can re'āyat kardan be used to mean 'observing' something with your eyes?

No. re'āyat kardan only means 'to observe' in the sense of complying with rules, maintaining standards, or respecting guidelines. If you want to say 'look at' or 'watch' something with your eyes, you would use a verb like negāh kardan.