Learn Icelandic: Stundum kemur læknirinn heim. - Sometimes the doctor comes home.

This happens because of the V2 (verb-second) rule. In Icelandic, the main verb usually needs to be the second piece of information in a sentence. Since this sentence starts with the adverb stundum (sometimes), the verb kemur must come right after it, pushing the subject læknirinn into the third spot.

Why use heim instead of heima?

Heim implies movement towards a place, like saying homewards. Because the doctor is actively coming (kemur) to the house, we use the motion word heim. If the doctor was already inside and not moving, you would use the stationary word heima.

Where is the word for 'the' in læknirinn?

In Icelandic, the word for 'the' (the definite article) is attached to the end of the noun instead of being a separate word. The base word for doctor is læknir, and adding the ending -inn turns it into læknirinn (the doctor).

What is the base form of the verb kemur?

The base form (infinitive) is koma (to come). It changes to kemur here because it matches a third-person singular subject, læknirinn (the doctor).