"The woman drinks her coffee."
Translation:Kvinnan dricker sitt kaffe.
You can think of coffee in two ways in Swedish, either as "a cup of coffee", which is "en kaffe", or more like "coffee in general", which is "ett kaffe", the main gender of the word. So if you say "en kaffe", you're sort of really saying "en (kopp) kaffe", just omitting the "cup" part of it.
Welcome to the reality of English being one of the very easiest language on this planet. And it really isn't a different rule for every word, there are distinct patterns.
It's just that English speaking peoole who've never learned another language have never been faced with more than the article "the" and are therefore never confronted with slightly more complicated grammar rules.
PS: Swedish is still a freakin breeze compared to German (as one example)!