Olet siis jo valmis.

In Finnish, the subject pronoun is often left out when the verb ending already shows who the subject is.

• olet = you are (2nd person singular)
• The ending -t tells you it means you

So Olet siis jo valmis is a very natural Finnish sentence.
You can say Sinä olet siis jo valmis, but adding sinä usually gives extra emphasis, like:

• You are already ready
• So you’re already ready

Without sinä, the sentence sounds more neutral and natural in many situations.

Olet is the 2nd person singular form of the verb olla (to be).

Here is the present tense of olla:

• minä olen = I am
• sinä olet = you are
• hän on = he/she is
• me olemme = we are
• te olette = you are
• he ovat = they are

So in this sentence:

• olet = are

It is the verb of the sentence.

Siis is a very common Finnish word with meanings like:

• so
• then
• therefore
• in that case

In this sentence, siis gives a sense like:

• so
• so then
• in that case

It often connects the sentence to something said or understood earlier.

For example, the feeling might be:

• Oh, I see — so you’re already ready.
• So, you’re already ready then.

It is not always strongly logical like English therefore; in everyday speech it is often just a discourse word that helps connect ideas.

Jo usually means already.

It shows that something has happened, or is true, earlier than expected or by this point.

So:

• valmis = ready
• jo valmis = already ready

In many contexts, jo adds a small feeling of surprise, progress, or comparison with expectations:

• You’re ready already?
• So you’re already ready.

It is a very common word in Finnish.

Valmis is an adjective, and here it means ready.

In this sentence it works as a predicative adjective after the verb olla:

• olet valmis = you are ready

This is similar to English:

• You are ready
• verb are
  • adjective ready

So valmis is describing the subject (you), not acting like an object.

Because after olla (to be), Finnish often uses the adjective in its basic form when describing what someone or something is like.

So:

• olet valmis = you are ready
• hän on iloinen = he/she is happy
• ruoka on kylmä = the food is cold

This is normal predicate-adjective structure in Finnish.

You may see other forms of valmis in different structures, for example:

• valmiina = in a ready state / ready
• valmiiksi = into a finished/ready state

But in this sentence, the plain form valmis is the normal choice.

Yes, Finnish word order is fairly flexible, but different orders create different emphasis.

The given order is natural and neutral:

• Olet siis jo valmis.

Roughly:

• olet = are
• siis = so/then
• jo = already
• valmis = ready

Other orders are possible, for example:

• Olet jo valmis. = You are already ready.
• Siis olet jo valmis. = So, you’re already ready.
• Jo olet valmis. = possible in special contexts, but less neutral
• Valmis olet jo. = marked/emphatic, poetic, or contrastive

So the sentence you have is a normal conversational order, with siis and jo placed before the adjective.

Yes.

If you remove siis, the sentence becomes:

• Olet jo valmis.

That still means You are already ready, and it is perfectly natural.

Adding siis makes the sentence feel more connected to earlier context, as if the speaker is reacting, concluding, or acknowledging something:

• Olet jo valmis. = neutral statement
• Olet siis jo valmis. = So, you’re already ready.

Yes.

Without jo, you get:

• Olet siis valmis.

That means So, you’re ready.

The sentence is still correct, but the idea of already disappears.
So jo is important if the speaker wants to show that the readiness has happened by now, perhaps sooner than expected.

It is neutral and can be used in both speech and writing.

A few notes:

• It uses the singular you form (olet), so it is addressing one person
• It does not include the pronoun sinä, which sounds natural and common
• It is neither especially formal nor especially slangy

If you wanted to be more formal when addressing one person politely, Finnish often uses the plural polite form:

• Olette siis jo valmis.

That is the formal/polite you are.

But the original sentence is the normal everyday way to say it to one person.

A very natural question form is:

• Oletko siis jo valmis?

Finnish often makes yes/no questions by adding -ko/-kö to the verb:

• olet = you are
• oletko? = are you?

So:

• Olet siis jo valmis. = You are already ready then.
• Oletko siis jo valmis? = So, are you already ready?

This is one of the most useful Finnish question patterns to learn.

The negative sentence is:

• Et siis ole vielä valmis. = So, you are not ready yet.
• or simply Et siis ole valmis. = So, you are not ready.

Finnish negation uses a special negative verb:

• en = I do not
• et = you do not
• ei = he/she does not
• etc.

So for you are not, Finnish uses:

• et ole

Notice that the main verb changes form:

• olet = you are
• et ole = you are not

Also, opposite to jo (already), Finnish often uses vielä (yet/still) in negative sentences:

• jo = already
• vielä = yet / still

So:

• Olet jo valmis. = You are already ready.
• Et ole vielä valmis. = You are not ready yet.

No. Valmis can describe people, things, work, food, plans, and more.

Examples:

• Olen valmis. = I am ready.
• Ruoka on valmis. = The food is ready.
• Työ on valmis. = The work is finished/ready.
• Suunnitelma on valmis. = The plan is ready.

So in Finnish, valmis can mean both:

• ready
• finished / completed

The exact nuance depends on context.