Learn Icelandic: Við eigum bara ein skæri hér. - We only have one pair of scissors here.

Because skæri (scissors) is a plural-only noun, just like in English. When counting plural-only nouns in Icelandic, we must use special plural numbers called distributive numerals. The neuter plural form of the distributive numeral for one is ein.

Wait, isn't ein the feminine singular word for 'one'?

It is! But it is also the neuter plural distributive form. The plural distributive forms for one are einir (masculine), einar (feminine), and ein (neuter). Since skæri is a neuter plural noun, we use ein.

Why does the sentence use eigum instead of höfum for the word 'have'?

The verb eiga is used for actual ownership or possession of physical objects, like a pair of scissors. The verb hafa is used mostly as a helping verb (for example, in 'we have finished') or for abstract concepts and physical traits.

If I wanted to say 'two pairs of scissors', how would I change ein?

You would use the neuter plural distributive numeral for two, which is tvenn. So two pairs of scissors is tvenn skæri. Three pairs would be þrenn skæri, and four pairs would be fern skæri.