"We speak fluent Spanish."
Translation:Puhumme sujuvaa espanjaa.
I'd say you're safe to replace "he" with "ne" in your spoken Finnish. It may feel a little awkward or rude, but trust me, it's not. Same with "hän" and "se".
It's also for sure worth it to find a Finn or Finnish-speaking person to talk to and practice with! That's probably the best thing you can do since your Finnish looks pretty fluent to me. Käy vaikka joskus toiste Suomessa ja käytä ehdottomasti niin paljon suomea kun pystyt käyttämään siellä! Jos ei kieltä käytä arkisissa tilanteissa, niin ei sitä täysin opi.
If you're asking perhaps for the difference between "sujuvasti" and "sujuvaa" here, that's the equivalent of the English adverb "fluently" and and adjective "fluent". So the orginal sentence is "We speak fluent Spanish" and "Puhumme espanjaa sujuvasti" is more literally "We speak Spanish fluently". Sujuva is in the partitive as it's an adjective describing the object, so it has to match the object. (Objects are almost always in the partitive with the verb puhua.)
I don't know if you're aware of puhekieli or if they're planning on rolling it out here, but the most natural in my mind is "Puhutaan espanjaa sujuvasti" if you were speaking casually with someone.
I understand completely. Puhekieli is a lot more difficult to follow at times.
However, because puhekieli is really what Finns use, I'd recommend learning it alongside kirjakieli, especially if you're serious about Finnish. It really makes a difference. Especially the third person plural forms in puhekieli. Almost no one uses the kirjakieli third person plural in spoken language, so it can really make you stand out when you're using it, sometimes making Finns aware they might need to switch to English. (I've experienced this, friends have experienced this. It's not great, but it's definitely a reality.)
@jennanen - I know, I realized I sounded like a twat when saying "sanovat" instead of "sanoo" etc., so I (mostly) stopped doing that. But I'm really not sure if I should continue using "he" or replace that with "ne" everywhere (it sounds rude to me).
And besides, I rarely get to speak to a Finn. Even though Praha is a popular destination for Finns, I rarely meet anyone to talk to. And so far I've only been to Finland once - kävin kerran Helsingissä juhannuksen aikana ja kaupunki oli tietenkin aika tyhjä, joten silloinkaan en saanut puhua kenellekään :D