Käytyäni kerhohuoneessa juttelin uuden naapurin kanssa vielä pihalla.

Here käytyäni means after I had been / after visiting.

So Käytyäni kerhohuoneessa... is a compact way to say something like:

After I had been in the club room...
or
After visiting the club room...

It gives the background action that happened before the main action juttelin.

Käytyäni is a special Finnish time-expression form often used to mean after doing something.

You can think of it like this:

• käydä = to go / visit / stop by
• käytyä = a form used in this time construction
• -ni = my / I, showing that I am the one who did the action

So käytyäni literally works like after my visiting, but in natural English it becomes after I had visited or after visiting.

This kind of form is very common in written Finnish and fairly common in careful spoken Finnish too.

Yes, the meaning is very close.

These are roughly equivalent:

• Käytyäni kerhohuoneessa...
• Kun olin käynyt kerhohuoneessa...

Both mean after I had been to / after I had visited the club room.

The version with käytyäni is more compact and stylistically a bit more formal or written-like. The kun olin käynyt version is more straightforward for learners and very clear in everyday language.

Because käydä usually takes the place in a location case like -ssa/-ssä when it means to visit / to stop by / to go somewhere and be there briefly.

So:

• käydä kerhohuoneessa = to visit / stop by the club room
• mennä kerhohuoneeseen = to go into the club room

Even though English often uses to with visit/go to, Finnish uses -ssa/-ssä with käydä.

So kerhohuoneessa is the normal form here.

Juttelin is:

• 1st person singular
• past tense (imperfect)

It comes from jutella = to chat / to talk

So:

• juttelen = I chat / I am chatting
• juttelin = I chatted / I was chatting

The ending -in tells you it means I in the past.

Because kanssa means with, and the noun before it normally goes into the genitive.

So:

• uusi naapuri = a new neighbor
• uuden naapurin = of a new neighbor / new neighbor's form, but here simply the form required before kanssa
• uuden naapurin kanssa = with the new neighbor

This is a very common pattern in Finnish:

• ystävän kanssa = with a friend
• äitini kanssa = with my mother
• opettajan kanssa = with the teacher

Vielä often means still, yet, or even depending on context.

In this sentence, it gives the idea of still / in addition / after that. It suggests that after being in the club room, the speaker continued or also chatted with the new neighbor out in the yard.

So the nuance is something like:

• I also chatted with the new neighbor out in the yard
• I was still chatting with the new neighbor in the yard
• After that, I chatted with the new neighbor in the yard as well

The exact best English wording depends on the larger context.

Pihalla is the usual Finnish way to say in the yard / out in the yard / outside in the courtyard.

It uses the ending -lla/-llä, which is the adessive case.

With many outdoor places and areas, Finnish often uses this case naturally:

• pihalla = in the yard
• kadulla = on the street
• torilla = at the market square
• asemalla = at the station

So even though English says in the yard, Finnish idiomatically says pihalla.

Because Finnish often leaves out subject pronouns when the verb ending already makes the subject clear.

Here:

• juttelin already means I chatted
• käytyäni also includes -ni, which shows I

So adding minä would usually be unnecessary unless you want extra emphasis.

This is very normal in Finnish:

• Menin kotiin. = I went home.
• Söin jo. = I already ate.
• Juttelin naapurin kanssa. = I chatted with the neighbor.

Finnish often puts a time or background element first to set the scene before the main event.

So the structure is:

1. Käytyäni kerhohuoneessa = after I had visited the club room
2. juttelin uuden naapurin kanssa vielä pihalla = I chatted with the new neighbor out in the yard

This order feels very natural because it tells you when/after what the main action happened.

If you changed the order, the sentence could still be understandable, but this version is smooth and natural because it presents the earlier action first.