Learn Dutch: Ze eten vanavond soep in de keuken. - They are eating soup in the kitchen this evening.

This is because of an important Dutch word order rule: Time before Place. In Dutch, time words like vanavond (this evening) usually come as early as possible after the verb, and they always come before a place like in de keuken (in the kitchen).

Where does the object (soep) go when you have both a Time and a Place?

The general rule of thumb is Time - Object - Place. So soep (the object) goes right after the time (vanavond) and before the place (in de keuken).

Ze can mean 'she' or 'they'. How do we know it means 'they' in this sentence?

You can always tell by looking at the verb! The verb eten is plural (the 'we/you all/they' form). If the sentence meant 'she', the verb would be singular: Ze eet vanavond soep...

Why does eten translate to 'are eating' instead of just 'eat'?

Dutch doesn't have a separate verb form for things happening right now (like the English '-ing'). The simple present tense eten can mean 'eat', 'are eating', or even 'will eat' depending on the context. Because of vanavond, 'are eating' makes the most sense in English.