Learn Dutch: De zolder is muf omdat we er nooit komen. - The attic is musty because we never come there.

In the middle part of a Dutch sentence, the little word er likes to be placed as early as possible. It almost always sits right after the finite verb or the subject. It also must come before negation words like nooit (never) or niet (not), as well as before adverbs of time, manner, and place.

What does er mean here, and could I use daar instead?

Here, er acts as an unstressed word for location, meaning "there" or "in it". It refers back to De zolder (the attic). You could grammatically use daar (there), but er is much more natural because you aren't emphasizing the location.

Why is the verb komen at the very end of the sentence?

The conjunction omdat (because) introduces a subordinate clause. A core rule in Dutch is that in subordinate clauses, all verbs get pushed to the very end. That is why it is omdat we er nooit komen instead of omdat we komen er nooit.

Why use komen (to come) instead of gaan (to go)?