It's kände when you're actively talking about the person doing the feeling, so e.g. jag kände [something].
But it's kändes when you're talking about the object that is being felt, so e.g. soffan kändes mjuk ("the sofa felt soft") - it means that it felt soft to somebody, but you're talking about the sofa rather than that person.
Note that there is as well a third variant with a reflexive pronoun, which is also for when you're actively talking about the person doing the feeling, and they're feeling something about or within themselves. For example: jag kände mig hungrig ("I felt hungry"). I see that you're also doing Spanish Duolingo, perhaps you've seen the same thing there, e.g. "me siento".
oh that was nice to read - simple and clear. I was ok with the reflexive part (thanks, as you pointed out to Spanish) but the first 2 paragraphs was where I was really confused. And now...Am I wrong in my understanding that känna also means to know like conocer and not saber? And if it is, any guidelines on that?
Glad to hear it helped!
You're right, it's used both for knowing somebody and for feeling something - and also for knowing about something ("känna till", where the "till" particle cannot be left out). I can't think of any grammatical rule to distinguish them, but the choice is usually fairly easy to derive contextually.
Is there some example where I can say "Jag kändes (something)..." or it's only used for the objects? Tack