Ovaj kaput ti dobro stoji.

Because kaput is a masculine singular noun, and ovaj has to agree with it in gender, number, and case.

• ovaj kaput = this coat
• ova jakna = this jacket
• ovo odijelo = this suit

Here, kaput is the subject of the sentence, so it is in the nominative singular, and ovaj matches that.

Kaput is in the nominative singular.

In this sentence, ovaj kaput is the thing being talked about as the subject: This coat suits you / looks good on you.

So the structure is roughly:

• ovaj kaput = subject
• ti = to you
• dobro stoji = looks good / suits

Yes, ti here means to you, not the subject you.

It is the dative singular form of the pronoun ti. Croatian often uses the dative with verbs and expressions that mean something like suit someone, please someone, help someone, and so on.

So:

• ti = to you
• meni = to me
• mu = to him
• joj = to her
• nam = to us

In this sentence, stajati nekome means to suit someone / look good on someone.

Yes, the basic meaning of stajati is to stand. But in Croatian, this verb is also commonly used with clothes to mean:

• look good on
• suit
• sometimes fit well

So Ovaj kaput ti dobro stoji literally looks like This coat stands well to you, but idiomatically it means This coat looks good on you or This coat suits you.

This is a very natural Croatian expression.

Because dobro is an adverb, and it modifies the verb stoji.

• dobar = good, masculine adjective
• dobra = good, feminine adjective
• dobro = well, in a good way

Here we are not describing the coat itself as good. We are describing how it looks on you, so Croatian uses the adverb:

• dobro stoji = looks good / suits well

Compare:

• Ovo je dobar kaput. = This is a good coat.
• Ovaj kaput ti dobro stoji. = This coat looks good on you.

Usually it mainly refers to how the clothing looks on someone.

So the sentence most naturally means:

• It suits you
• It looks good on you

Depending on context, it can also suggest that the coat fits nicely, but the main idea is usually appearance, not exact size.

If you specifically want to talk about size, Croatian might use other expressions too, such as:

• Kaput ti je velik. = The coat is big on you.
• Kaput ti je malen. = The coat is small on you.
• Kaput ti odgovara. = The coat fits/suits you.

Yes. Tebi is the full form, while ti is the short clitic form.

• Ovaj kaput ti dobro stoji. = neutral, everyday
• Ovaj kaput tebi dobro stoji. = more emphatic, like This coat looks good on you

Croatian often uses the short form unless there is a reason to emphasize or contrast:

• Meni ne stoji dobro, ali tebi stoji. = It doesn’t look good on me, but it does on you.

Croatian word order is fairly flexible, but ti is a clitic, so it usually goes in second position in the clause.

That is why Ovaj kaput ti dobro stoji sounds natural.

You may also hear:

• Ovaj ti kaput dobro stoji.
• Dobro ti stoji ovaj kaput.

These are all possible, but the placement of short pronouns like ti follows clitic-position rules rather than simple English-style word order.

For a learner, Ovaj kaput ti dobro stoji is an excellent standard pattern to remember.

Grammatically, yes, but the meaning changes or becomes less complete.

• Ovaj kaput dobro stoji. could sound like This coat hangs well / sits well / looks good, but it no longer clearly says on you.
• Ovaj kaput ti dobro stoji. clearly means This coat suits you.

Since the point of the sentence is usually who the coat looks good on, ti is important.

Yes. A very common alternative is pristajati.

For example:

• Ovaj kaput ti dobro pristaje.

This also means This coat suits you.

A rough comparison:

• stajati with clothes often feels very natural for look good on
• pristajati also means suit, often in a slightly broader sense

In everyday speech, both are common and useful.

No. The verb in this sentence is already stoji.

English often uses is in descriptions, but here Croatian is not making a simple X is Y statement. It is using the full verb stajati:

• stoji = stands / suits / looks on

So there is no missing je here. The sentence is already complete.

In some contexts, yes.

Here, ovaj is being used as a determiner before a noun:

• ovaj kaput = this coat

But Croatian ovaj can also stand on its own:

• Ovaj mi se sviđa. = I like this one.

So in your sentence, it simply means this because it directly modifies kaput.

It is neutral and very natural. The pronoun ti makes it informal singular, used when speaking to one person you address as ti.

If you wanted to be polite or address more than one person, you would use vam:

• Ovaj kaput vam dobro stoji. = This coat looks good on you.

So:

• ti = informal singular
• vam = polite singular or plural

You can simply add ne before the verb:

• Ovaj kaput ti ne stoji dobro.

That means:

• This coat doesn’t look good on you
• This coat doesn’t suit you

You may also hear:

• Ovaj kaput ti loše stoji. = This coat looks bad on you.

Both are natural.