Learn Swedish: Delikatessen säljer fina ostar och dyra teer. - The delicatessen sells fine cheeses and expensive teas.

This sentence uses sortpluralis (plural of kind or variety). When an uncountable mass noun is put into the plural, it refers to different types, brands, or portions of that substance. Here, ostar means varieties of cheese (or whole cheese wheels) and teer means varieties of tea.

Te is an ett-word. Why is its plural form teer instead of staying the same?

While most ett-words ending in a consonant look the same in the plural, te is a loanword ending in a stressed vowel. In Swedish, these typically take the -er suffix in the plural. Therefore, ett te becomes teer when referring to types of tea, just like ett kafé becomes kaféer.

Does Delikatessen refer to a piece of food or the shop?

While en delikatess literally translates to a delicacy (a fine food item), it is widely used to refer to the delicatessen shop itself or the deli counter. Here it is in the definite form (-en) to mean the deli, which is why it can act as the subject selling (säljer) items.

Do adjectives modifying a mass noun in sortpluralis follow standard plural agreement rules?