kono kafe ha sizuka nanode, tomodati to kigaru ni hanasemasu.

は is the topic marker. It tells you that the sentence is about this café.

So このカフェは is like saying:

• As for this café, ...
• This café, ...

In English, we usually do not mark topics this explicitly, so it often just becomes This café is... or Because this café is...

静か is a な-adjective.

With な-adjectives:

• before a noun: 静かなカフェ = a quiet café
• as a predicate: カフェは静かです = The café is quiet

In your sentence, 静か is not directly modifying a noun. It is part of 静かなので, so you use 静か, not 静かな.

なので means because or so, and it gives a reason in a fairly soft, explanatory way.

So:

• このカフェは静かなので、... = Because this café is quiet, ...

It often sounds a little less blunt and a little more connected than だから.

Also, after a noun or な-adjective, this pattern is very common:

• 学生なので = because (someone) is a student
• 便利なので = because it is convenient
• 静かなので = because it is quiet

Both can mean because / so, but the nuance is a little different.

• だから often feels more direct and standalone.
• ので / なので often feels a bit softer, more explanatory, and slightly more formal or neutral.

Compare:

• 静かだから、話せます。
• 静かなので、話せます。

Both are natural, but なので sounds a little smoother and more descriptive in this kind of sentence.

気軽に means something like:

• casually
• comfortably
• without feeling pressure
• at ease

So 友達と気軽に話せます is not just can talk with friends. It has the feeling of:

• can chat comfortably with friends
• can talk with friends without feeling awkward or tense

It suggests a relaxed atmosphere.

Because 気軽 is a な-adjective, and に is how you often turn a な-adjective into an adverb.

So:

• 気軽な会話 = casual/easygoing conversation
• 気軽に話す = to talk casually / comfortably

This is similar to how English changes easy into something like easily, though the grammar is not identical.

Here, と marks the person you do the action with.

So:

• 友達と話す = talk with a friend / talk with friends

With 話す, と is very common for the conversation partner.

Even though English often says talk to a friend, Japanese usually uses と for the person you are speaking with in this kind of mutual conversation.

Sometimes, but it changes the nuance.

• 友達と話す = talk with a friend
• 友達に話す = talk to a friend / tell a friend something

に can sound more one-directional, as if you are saying something to them, rather than having a back-and-forth conversation.

In this sentence, because the idea is casually chatting with friends, 友達と is the natural choice.

話せます is the potential form of 話す, so it means can talk.

• 話します = talk / will talk
• 話せます = can talk

The sentence is not simply saying that you talk there. It is saying that, because the café is quiet, talking with friends is possible, easy, or comfortable there.

So the potential form fits the meaning very well.

Not really. Here it is more about situational possibility than personal skill.

It does not mean:

• I have the ability to speak

It means more like:

• I can talk here
• It’s easy to talk here
• This place makes conversation possible/comfortable

The reason is the environment: the café is quiet.

It can be either.

Japanese nouns often do not explicitly show singular vs. plural unless the speaker wants to make it clear.

So 友達と could mean:

• with a friend
• with friends

You decide from context or from the translation you are given.

Yes, possibly.

Japanese very often leaves out subjects when they are obvious from context. So this sentence could imply:

• I can talk comfortably with friends
• We can talk comfortably with friends
• You can talk comfortably with friends

depending on the situation.

The sentence itself focuses more on the condition and result:

• This café is quiet
• therefore casual conversation with friends is possible

The structure is:

• このカフェは = as for this café
• 静かなので = because it is quiet
• 友達と = with friends
• 気軽に = casually / comfortably
• 話せます = can talk

A very literal order would be:

As for this café, because it is quiet, with friends comfortably can talk.

That sounds unnatural in English, of course, but it helps show how Japanese builds the sentence.

Those spaces are just for learners.

Normal Japanese is usually written without spaces:

このカフェは静かなので、友達と気軽に話せます。

So if you see the sentence with spaces, that is a teaching aid, not standard writing.