Learn Arabic (Modern Standard): بدأ الخبير نفسه تقطير الماء والورد. - The expert himself started the distillation of the water and the rose.

While نفس literally means "soul" or "self," it is often used in Arabic grammar to add emphasis. When it directly follows a definite noun and attaches a matching pronoun suffix (here, the ـه referring back to الخبير), it translates to "himself" or "the very same."

Why is there no definite article (الـ) on the word تقطير (distillation) if the translation says "the distillation"?

It is the first part of an idaafa (genitive construction) with the next word, translating to "distillation of the water." The rule in an idaafa is that the first word never takes الـ (al-), even though it is understood as definite because the second word (الماء) is definite.

What pattern does the noun تقطير (distillation) follow?

It follows the تفعيل (taf'eel) pattern. At the B1 level, whenever you see a verbal noun (masdar) on this specific pattern, you can reliably guess it belongs to a Form II verb. Here, it comes from the verb قطّر (to distill/drip).

Can you use a verb instead of the noun تقطير to say "started to distill"?

Yes! Verbs of beginning like بدأ can be followed by either a noun acting as an object (as it is here) or by a present tense verb. Instead of saying "started the distillation" with the noun, you could say بدأ يقطّر (started to distill) using the present tense verb.