Learn Icelandic: Það eru fimm hestar úti. - There are five horses outside.

The singular form is hestur (horse). For many masculine nouns that end in -ur, you form the nominative plural by dropping the -ur and adding -ar.

Why do we use eru instead of er right after Það?

Even though the sentence starts with Það (there/it), the actual subject of the sentence is the plural phrase fimm hestar. The verb must match this plural subject, so we use eru (are).

Does the number fimm change endings to match the gender of the horses?

No. In Icelandic, only the numbers 1 through 4 change their form to match the gender and case of the noun. Numbers from 5 and up, like fimm, always keep the exact same form.

I sometimes see út for outside. Why is it úti in this sentence?

Icelandic has different words for location versus movement. You use úti when something is already located outside, like these horses. You use út for movement, like when someone is walking outside.