Yes you can choose courses from programme taught in Icelandic if the course is taught in English or other languages you already speak if the programme is a language programme.
Programmes taught in Icelandic require fluent Icelandic but some courses within the programme may be taught in English or other languages.
The courses taught in English or other languages are intended for foreign students.
You find the language marking of the course on the study programme page and in the course catalogue.