Questions & Answers about Ik zag haar op het stationsplein.
Why is there an s in the middle of stationsplein?
Stationsplein is a compound noun made from station and plein (square). In Dutch, an extra -s- (called a tussen-s or linking-s) is often added between two nouns when combining them. While the rules can be tricky, you generally use it if you can naturally hear the s sound when pronouncing the combination, or if the first word (station) commonly takes an -s- in other compounds, like stationsstraat (station street) or stationshal (station concourse).
Why is the article het used for stationsplein?
The gender (and therefore the article) of a Dutch compound noun is always determined by its final part. Since the word for square is het plein, any compound ending in plein will also be a het word. The first word doesn't change the article, even if it has a different gender (though in this specific case, station also happens to be a het word).
Why do we use the preposition op here instead of in?
In Dutch, you use op (on) for being physically present in open public spaces. Just as you say you are op straat (on the street), you say you are op het plein (on the square).
Is zag an irregular verb form?