Learn Dutch: Ze bestellen drie cappuccino's en vier cola's. - They are ordering three cappuccinos and four colas.

In Dutch, when a noun ends in a single open vowel like a, i, o, u, or y, you must add an apostrophe before the plural -s. This tells you to keep the vowel sound long. If you just wrote colas, the rules of Dutch spelling would make it sound like a short a.

How can I tell that ze means they and not she in this sentence?

You can tell by looking at the verb that follows it. The verb bestellen is in its plural form. If the sentence was about a single female, it would use the singular verb form: ze bestelt.

Why does the English translation say are ordering when the Dutch word is just bestellen?

Dutch does not have a separate continuous tense like English does with am/is/are plus -ing. The present tense verb bestellen covers both they order and they are ordering. You just pick the one that makes the most sense in context.

I thought Dutch plurals usually end in -en. Why do these end in -s?

While many Dutch words do take -en to become plural, there are two reasons why these words take an -s instead. First, words that end in a vowel almost always trigger an -s plural. Second, they are words borrowed from other languages, which also typically get an -s plural in Dutch.