Learn Icelandic: Þau eiga aðra stóla og önnur húsgögn. - They have other chairs and other furniture.

The word for "other" (annar) must match the noun it describes in gender, number, and case. Stóla (chairs) is a masculine plural noun in the accusative case, so it takes aðra. Húsgögn (furniture) is neuter plural accusative, so it takes önnur.

Why are aðra stóla and önnur húsgögn in the accusative case?

They are the direct objects of the verb eiga (to own/have). In Icelandic, physical possessions typically take the accusative case after this verb.

Is húsgögn plural? In English, "furniture" is a singular uncountable word.

Yes, húsgögn is a plural neuter noun. While English treats "furniture" as a singular mass noun, Icelandic uses the plural to refer to furniture in general. If you were talking about just one piece of furniture, you would use the singular form, húsgagn.

Why use eiga for "have" instead of hafa?

When "have" means "to own" physical possessions like chairs, Icelandic uses eiga. The verb hafa is usually reserved for abstract things (like having an idea or having time) or used as a helper verb (like "have eaten").