Learn Dutch: Ze lopen met één hond naar de stad. - They walk to the city with one dog.

This is the vowel-dropping rule in action! When we add -en to make the plural, the word breaks into syllables as lo-pen. The first syllable (lo-) ends in a vowel, which makes it an 'open' syllable. Vowels in open syllables are naturally long, so we drop the extra o because one is enough to make the long 'o' sound.

Could Ze mean 'she' in this sentence?

Ze can mean 'she' or 'they', but here it has to mean 'they'. We know this because the verb is in the plural form (lopen). If it meant 'she', the verb would use the singular form: Ze loopt.

Why are there accent marks on the word één?

The accents are used to emphasize that we mean the number 'one', not just 'a' or 'an'. In Dutch, een without accents is the article 'a'. Writing één makes it clear that they are walking with exactly one dog.

The word hond ends in a 'd', but it sounds like a 't' when spoken. Is that right?

Yes! In Dutch, any d at the very end of a word is pronounced like a 't'. If you ever forget how to spell it, try making the word plural: in honden (dogs), the d moves to the middle of the word and you can clearly hear the 'd' sound again.