Η νέα σου ιδέα φαίνεται πολύ καλή.

This is the most neutral and natural order in Greek for your new idea:

• Η = the
• νέα = new
• σου = your
• ιδέα = idea

Greek is more flexible than English with word order, but this order sounds very natural. You may also hear variations like η ιδέα σου or η καινούρια σου ιδέα, depending on emphasis and style.

Because it agrees with ιδέα, which is a feminine singular noun.

In Greek, adjectives change form to match the noun in:

• gender
• number
• case

Since ιδέα is feminine singular nominative, νέος (new) becomes:

• masculine: νέος
• feminine: νέα
• neuter: νέο

So:

• η νέα ιδέα = the new idea

σου means your.

More literally, it is the genitive form of the pronoun you (singular/informal), but in sentences like this it functions as a possessive:

• η ιδέα σου = your idea
• literally: the idea of you

Greek often uses these short pronoun forms after the noun:

• μου = my
• σου = your
• του / της = his / her
• μας = our
• σας = your
• τους = their

So η νέα σου ιδέα means your new idea.

In Greek, possessive pronouns like σου often come after the article/adjective area and before or after the noun, depending on the structure.

In η νέα σου ιδέα, the placement is very natural and means:

• your new idea

You will also commonly see:

• η ιδέα σου = your idea

The position of σου is something you gradually get used to through exposure. In this sentence, η νέα σου ιδέα is a normal, idiomatic phrase.

φαίνεται means seems or looks.

It comes from the verb φαίνομαι, which is often used for how something appears:

• φαίνεται καλό = it seems/looks good
• φαίνεται δύσκολο = it seems difficult
• φαίνεται πολύ καλή = it seems very good

So in this sentence, φαίνεται connects the subject your new idea with the description very good.

Because καλή has to agree with ιδέα, which is feminine singular.

The adjective καλός (good) changes form:

• masculine: καλός
• feminine: καλή
• neuter: καλό

Since ιδέα is feminine:

• η ιδέα είναι καλή = the idea is good

Here, after φαίνεται, Greek still uses the adjective in the form that matches the subject:

• Η ιδέα φαίνεται καλή = The idea seems good

Because πολύ here is an adverb, meaning very.

• πολύ καλή = very good

Greek distinguishes between:

• πολύ = very / much (adverb)
• πολλή = much / a lot of with a feminine noun or as an adjective-like form in some contexts

In this sentence, πολύ modifies the adjective καλή, so the correct form is:

• πολύ καλή

Compare:

• Είναι πολύ καλή. = She/it is very good.
• Έχει πολλή δουλειά. = She/he has a lot of work.

It can mean either, depending on context.

φαίνεται often covers both:

• seems
• looks
• appears

In this sentence, if we are talking about an idea, English usually prefers:

• Your new idea seems very good.

But the Greek verb itself is broader and can be translated in different ways depending on what sounds natural in English.

Because the sentence does not use είναι (is) here. Instead, it uses φαίνεται (seems/looks).

So the structure is:

• Η νέα σου ιδέα = subject
• φαίνεται = seems
• πολύ καλή = very good

Greek could also say:

• Η νέα σου ιδέα είναι πολύ καλή. = Your new idea is very good.

But that is a stronger, more direct statement.
With φαίνεται, the speaker is saying it appears or seems very good.

It is in the nominative singular, because it is the subject of the sentence.

You can tell from the article too:

• η ιδέα = nominative singular feminine

The whole subject is:

• Η νέα σου ιδέα = Your new idea

Then the verb is:

• φαίνεται

Yes. That is also correct.

Both νέα and καινούρια can mean new, though there can be slight differences in tone or nuance depending on context:

• νέα = new
• καινούρια = new, often with a slightly stronger sense of brand-new or recent

So:

• Η νέα σου ιδέα φαίνεται πολύ καλή.
• Η καινούρια σου ιδέα φαίνεται πολύ καλή.

Both are natural Greek.

A simple pronunciation guide is:

i NÉ-a sou i-THÉ-a FÉ-ne-te po-LÍ ka-LÍ

A few useful notes:

• η sounds like ee
• θ in ιδέα sounds like the th in think
• αι in φαίνεται sounds like e
• stress matters in Greek, so notice:
  • νέα
  • ιδέα
  • φαίνεται
  • πολύ
  • καλή

Normally, with this kind of noun phrase, Greek would keep the article:

• Η νέα σου ιδέα φαίνεται πολύ καλή.

Greek uses the definite article much more often than English.
Dropping η here would sound unnatural in standard Greek.

So even though English says your new idea without the, Greek naturally says:

• η νέα σου ιδέα

This is one of those places where Greek and English structure differ.