It says the correct translation is ''Мій сніданок - кава, хліб і сир.'' but why is кава there and not каву?
The sentence is My breakfast is coffee, bread and cheese. After My breakfast is... we use nominative case of nouns (basically, we NAME the items of the breakfast). Кава is nominative, каву is genitive or accusative (я люблю каву, я п’ю каву)