In order to be granted Finnish citizenship, you must pass a language test. This test is called the National Certificate of Language Proficiency, or YKI-testi in Finnish and allmänna språkexamen, or YKI-examen in Swedish. The level required for citizenship is B1.2 (mellannivå, intermediate level, level 3-4). You can familiarise yourself with the test here, in Swedish. You will find the test dates, the test centers, and information on how to register here. In the Capital Region the YKI test in Swedish, at the mellannivå/intermediate level, is offered by Arbis and Careeria in Helsingfors, and by Axxell and Omnia in Esbo. If you want to take the högsta nivå/advanced level test, you can do that at O&O in Helsinki.