Learn Russian: Стеклодув выдувает расплавленное стекло.

It is a compound noun made from стекло (glass) and the root of дуть (to blow). The two parts are joined by the connecting vowel о, which is a standard way to form compound words in Russian, much like водопад (waterfall).

What does the prefix вы- add to the base verb дуть in выдувает?

The prefix вы- typically indicates outward movement or achieving a specific result through an action. Here, выдувать (to blow out) describes the exact process of the glassblower forcing air outward into the material to create a shape.

Is расплавленное a standard adjective?

It functions as an adjective here, but it is actually a past passive participle derived from the perfective verb расплавить (to melt down). The double -нн- suffix is a classic marker of these participles, and the word literally translates to glass that has been melted.

Why does расплавленное use the prefix рас- instead of раз-?

The spelling of this prefix depends on the first letter of the root. Because the root here starts with п, which is a voiceless consonant, the prefix ends in the voiceless с (рас-) to match it, rather than the voiced з (раз-).