Questions & Answers about Þetta er úrið hans.
Why does hans come after the noun instead of before it?
In Icelandic, possessive words like hans (his) usually come right after the thing being owned. So instead of saying "his watch" like in English, you phrase it as "the watch his".
Why does the word úr (watch) have the definite article -ið attached to it?
When you put a possessive pronoun like hans after a noun, that noun must be in the definite ("the") form. Úr means "a watch", while úrið means "the watch". To say "his watch", you combine them to make úrið hans.
Would hans change if the object was a masculine or feminine noun instead of the neuter úrið?
No, it stays exactly the same! The word hans is an invariable genitive pronoun. That is a grammar term meaning its spelling never changes, no matter the gender, number, or role of the object being owned. It will always just be hans.