This is a great question to ask and gives other learners a realistic idea of what one can do with their TL at different levels, so I'll add my $0.02.
I've never been formally certified in Swedish, but according to a couple of my native speaker friends I'm in the void between B2 and C1, but closer to the C1 level (hence why my flair is "C1-ish").
I can hold a written and spoken conversation in Swedish and understand >99% of everything that is written or spoken by all of the native speakers that I converse with. Occasionally (I'd say probably once in every 20-30 messages) there might be a word or phrase I don't understand, but I'll be able to ask for clarification in Swedish and receive an explanation in Swedish so that I can correctly parse the word or phrase. This includes the daily slang used by my partner and my friends, as well as any dialectical differences that they use in their daily speech. When I'm talking with several of them at the same time, I still can interact with them but things are harder.
One of my friends has completely banned me from using English at all to communicate with him - so all interactions are in Swedish - and I don't have problems communicating with him.
When it comes to reading - I can understand (and correctly interpret) roughly 95% that is being said in articles that are aimed at native speakers who are in their final years of highschool in Sweden. Of the other 5%, approximately 3% of those words and phrases are things I can guess from context or by knowing the root words.
When it comes to things aimed at adult (and educated) native speakers I understand probably about 85% of things that are written, most of the remaining 15% is highly specific vocabulary, dialectical words, formal language (where I know a synonym for the word already, but a formal variant exists that I don't know), archaic language or similar. The book I'm currently working my way through, is a crime novel - which I understand 83% of the words (based directly off the stats I have in an assisted reader known as "Foreign Language Text Reader"), of which the remaining 17% are the words I mentioned above. I understand slightly more because I've already read the book's English translation, so I understand the plot and most of the details as a result - but individual adjectives (which don't really add a heap to the plot) might be unknown.
When it comes to listening - if it's about everyday topics I understand basically everything. More specialised topics depends on what the topic is - sometimes I understand almost everything, if it's a highly specific topic I'm not familiar with, I'll need the person to explain it further.
The limits of what I can do: Anything that's written or spoken in heavy dialect is a problem, as is the same with slang spoken at a high speed. Highly specific topics and jargon can also be problematic, depending on what the specific words are, and depending on if I already know a synonym of said word.