Learn Icelandic: Já, hann er Íslendingur.

er is the form of the verb vera (to be) used for the third person singular. You use it with hann (he), hún (she), and það (it). It is also the exact same word used for the first person: ég er (I am). Only the "you" form is different in this group: þú ert (you are).

Where is the word for "an" in this sentence?

Icelandic does not have a word for "a" or "an" (an indefinite article). When you want to say "an Icelander", you simply use the noun by itself: Íslendingur.

Does the ending of Íslendingur give us a clue about the word?

Yes! The -ur ending is a very common sign that a noun is masculine. Because this word refers to a male Icelander, it perfectly matches the masculine pronoun hann (he).

Why is Íslendingur capitalized?

Just like in English, nouns that refer to nationalities or people from a specific country are capitalized in Icelandic. However, when you later learn how to use nationalities as adjectives (like describing "Icelandic water"), those will be written with a lowercase letter.