Learn German: Wir erarbeiten eine neue Struktur für das Projekt. - We are developing a new structure for the project.

The prefix er- often expresses achieving a result or reaching a goal through an action. While arbeiten simply means "to work," erarbeiten means "to develop," "to work out," or "to produce" something through effort. In this sentence, it shows that the work is directed at successfully creating a new structure.

Notice how erarbeiten takes a direct object here (eine neue Struktur). Does the prefix change the grammar of the verb?

Yes! The base verb arbeiten is intransitive, meaning it doesn't take a direct object (you usually just "work on" something using a preposition). Adding the prefix er- typically makes a verb transitive, meaning it now requires an accusative direct object. You aren't just working; you are "working out" a specific thing (eine neue Struktur).

Could I use entwickeln instead of erarbeiten to mean "developing" here?

Yes, Wir entwickeln eine neue Struktur is very similar and perfectly natural. However, erarbeiten specifically emphasizes the active, step-by-step hard work and effort put into creating that structure, whereas entwickeln focuses more generally on the evolution or design process.

I've seen this verb used reflexively, like "sich etwas erarbeiten". Could we say "Wir erarbeiten uns eine neue Struktur"?

You could, but it changes the nuance slightly. Using it as a dative reflexive verb (Wir erarbeiten uns...) implies earning or acquiring something for oneself through hard work (e.g., "We are earning/working out a new structure for ourselves"). The non-reflexive version in this sentence is better suited for an objective task being done for the project as a whole.