Learn Dutch: Het duurt grofweg drie jaar. - It takes roughly three years.

The suffix -weg is used to turn the adjective grof (coarse or rough) into an adverb. While -weg often adds a sense of "simply" or "just" (like in simpelweg), here it creates an adverb of degree meaning "roughly" or "broadly."

Could I just use ongeveer instead of grofweg in this sentence?

Yes, ongeveer means "approximately" or "about" and is perfectly natural here. Grofweg adds a slight nuance of being a rough estimate or a broad generalization, much like "roughly" versus "about" in English.

Why is the singular jaar used after the number drie?

In Dutch, nouns expressing a unit of time, measurement, or weight usually remain singular when they follow a specific number greater than one. This is why you say drie jaar (three years), twee uur (two hours), or vijf kilo (five kilos).

Why does the Dutch sentence use duurt instead of a literal translation of "takes", like neemt?

In English, we say that an activity "takes" time, but Dutch uses the verb duren (to last or to take a certain amount of time). You cannot use nemen to express that an event takes time.