The document discusses the genitive case in Finnish. It notes that the ending of the singular genitive is -n. It is used to express possession like in English. The stem form without the -n ending is needed to form other cases in Finnish. It also discusses consonant changes that occur in different cases, like t becoming d, and provides examples like katu becoming kadun in the genitive case. It includes a table showing the main consonant changes that are integral to the Finnish language.