kono kikai no sousa ha sukosi hukuzatu nanode, setumeisyo wo yomimasu.

It has two parts:

• この機械の操作は少し複雑なので = because operating this machine is a little complicated
• 説明書を読みます = I will read the manual

A very common Japanese pattern is:

reason + ので/から + main action

So the reason comes first, and the result/action comes after.

Here, の connects two nouns:

• この機械 = this machine
• 操作 = operation / use / handling

So この機械の操作 means:

• the operation of this machine
• how to operate this machine
• using this machine

You can often think of A の B as B of A or A’s B, depending on what sounds natural in English.

は marks the topic.

So この機械の操作は means:

• as for operating this machine...
• when it comes to using this machine...

The sentence is talking about the topic この機械の操作 and then saying something about it: it is a little complicated.

If you used が instead, the nuance would change a bit. は is more natural here for introducing the topic and making a general comment about it.

複雑 is a na-adjective.

With ので, a na-adjective usually connects like this:

• 静かなので
• 便利なので
• 複雑なので

So 複雑なので is the normal form.

A more polite version, especially in formal speech or writing, can be:

• 複雑ですので

But 複雑だので is not correct.

Both ので and から can mean because.

In many cases:

• ので sounds a little softer, more explanatory, and more objective
• から can sound more direct or more like the speaker’s personal reason

So here, 複雑なので feels like a calm explanation:

• because it is a little complicated

That fits well in polite speech.

少し means a little or somewhat.

So 少し複雑 means:

• a little complicated
• somewhat complicated

It softens the statement. Instead of saying the operation is flatly complicated, the speaker says it is only a bit complicated.

This is very natural in Japanese, since speakers often soften comments.

They are similar, and both can mean a little.

But the nuance is slightly different:

• 少し is a bit more neutral or formal
• ちょっと is more casual and conversational

So in this sentence, 少し sounds neat and natural.
If you said ちょっと複雑なので, it would also be understandable, but it would feel a bit more casual.

Japanese non-past can cover:

• present
• habitual action
• future action

Here, because of the context, 読みます is most naturally understood as future:

• I will read the manual
• I’m going to read the manual

The speaker is saying: because it is a little complicated, they will read the manual.

Japanese often leaves out the subject when it is clear from context.

So even though English usually needs I, Japanese does not have to say it.

This sentence naturally implies something like:

• I will read the manual
• we will read the manual

depending on the situation.

In most contexts, listeners can figure out who is meant without the pronoun being stated.

操作 means operation, handling, or use, especially of a machine or device.

In this sentence, it refers to how to operate the machine or the act of using it.

So この機械の操作 could be translated naturally as:

• operating this machine
• using this machine
• how to use this machine

English translation depends on what sounds most natural.

Japanese often puts background information before the main point.

So instead of:

• I’ll read the manual because operating this machine is a little complicated

Japanese often says:

• Because operating this machine is a little complicated, I’ll read the manual

This is very normal in Japanese. The listener gets the context first, then the main action.

No. Normal Japanese is usually written without spaces:

この機械の操作は少し複雑なので、説明書を読みます。

The spaces in your example are just for learners, to make the parts easier to see.