The official language in Oslo is Norwegian, and the standard form is known as Bokmål. Most Norwegians are fluent in English, and you'll find that English is widely spoken, especially in urban areas. 

Learning Norwegian can be a rewarding experience, although some newcomers may find it challenging due to its complex grammar and pronunciation. However, Norwegians generally appreciate efforts to speak their language, so learning some basic phrases and greetings can go a long way in making connections! There are several language schools and resources available, including The Oslo Adult Education organization or those offered by universities like the University of Oslo (uio.no). A great resource is this guide put together by the city of Oslo: oslo.kommune.no/english/welcome-to-oslo/learn-norwegian/how-to-find-the-right-course-for-you/#gref. Online platforms such as Duolingo (duolingo.com) and Babbel (babbel.com) also offer Norwegian language courses for beginners and intermediate learners.