Learn Dutch: We gaan er mijn verjaardag vieren. - We are going to celebrate my birthday there.

It uses the helper verb gaan (to go) combined with an infinitive. Just like in English, saying you are "going to" do something shows it will happen in the future. Here, gaan is conjugated to match we, and the infinitive vieren (to celebrate) gets pushed to the end.

Why is vieren placed at the very end of the sentence?

In Dutch, when you use a helper verb like gaan, the second verb (the infinitive) must move to the very end of the sentence. The conjugated verb (gaan) stays in the normal second position.

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

Er means "there" in a soft, unstressed way. You could use daar if you really wanted to emphasize the location, but er is much more common when the place isn't the main focus of the sentence.

Why does er come before mijn verjaardag?

The little word er almost always wants to sit as close to the conjugated verb as possible. It naturally tucks in right after gaan and before the direct object (mijn verjaardag).