This is the 103rd most frequent Icelandic word.
mars
The Icelandic word "mars" means "March" (the month) in English.
In this sentence, 'Mars' is used as a proper noun referring to the planet Mars in our solar system.
Mars er fjórða plánetan frá sólinni.
Mars is the fourth planet from the Sun.
Here, 'mars' refers to the month of March in the context of a calendar year.
Í mars byrjar það að hlýna eftir veturinn.
In March, it starts to warm up after the winter.
In this usage, 'Mars' refers to the branded chocolate bar available commercially.