Insomma, ci vediamo domani mattina in biblioteca.

Here insomma is a discourse marker, not a key part of the basic factual meaning.

Depending on tone and context, it can mean things like:

• so
• anyway
• all in all
• in short
• right, then

In Insomma, ci vediamo domani mattina in biblioteca, it sounds a bit like the speaker is wrapping things up or getting to the point: So, we’ll see each other tomorrow morning in the library, or Anyway, see you tomorrow morning in the library.

It does not usually need to be translated word-for-word every time.

Because vedersi is often used in Italian to mean to see each other or to meet.

• vediamo = we see
• ci vediamo = literally we see ourselves, but in normal usage it means we see each other / we’ll meet

The ci here is a pronoun meaning ourselves or, more naturally in this context, each other.

So:

• Vediamo il film = We watch the film
• Ci vediamo domani = We’ll see each other tomorrow

It is related to the reflexive form, but in this sentence it is best understood as reciprocal.

A quick distinction:

• reflexive: the action goes back to the subject itself
  
  • Mi lavo = I wash myself
• reciprocal: two or more people do the action to one another
  
  • Ci vediamo = We see each other

So although it uses the same kind of pronoun as reflexive verbs, here the meaning is reciprocal: we see each other.

Italian often uses the present tense to talk about the near future, especially when there is a clear time expression such as domani mattina.

So:

• Ci vediamo domani = literally present, but naturally We’re seeing each other tomorrow / See you tomorrow
• Parto stasera = I’m leaving tonight

This is very similar to English, where you can say I’m meeting him tomorrow even though the event is in the future.

Italian could also use the future tense in some contexts, but here the present is the most natural and common choice.

It can mean both, depending on context.

In a sentence like this, Ci vediamo domani mattina in biblioteca, the idea is:

• We’ll see each other tomorrow morning in the library
• more naturally in English: See you tomorrow morning in the library

Italian often uses ci vediamo as a very common way to say goodbye when you know you will meet again.

For example:

• Ci vediamo domani! = See you tomorrow!
• Ci vediamo dopo. = See you later.

Both mattina and mattino exist, but domani mattina is the much more common everyday expression for tomorrow morning.

So learners should strongly prefer:

• domani mattina

rather than:

• domani mattino — possible, but less usual in everyday speech

Also note that domani mattina is a fixed time expression. You do not need an article.

• Ci vediamo domani mattina = See you tomorrow morning

In Italian, with certain places and institutions, the article is often omitted after prepositions when the place is mentioned in a general way.

So:

• in biblioteca = in / at the library
• a scuola = at school
• in ufficio = at the office
• in chiesa = in church

Here in biblioteca sounds natural because it simply means the location where you will meet.

You may use an article when the place is more specific:

• nella biblioteca dell’università = in the university library
• nella biblioteca comunale = in the public library

So in biblioteca is general, while nella biblioteca... is more specific.

That word order is very natural in Italian: first the time, then the place.

So the sentence flows as:

• ci vediamo = we’ll see each other
• domani mattina = tomorrow morning
• in biblioteca = in the library

Italian is fairly flexible, so other orders are possible for emphasis, for example:

• Ci vediamo in biblioteca domani mattina.
• Domani mattina ci vediamo in biblioteca.

But Ci vediamo domani mattina in biblioteca is a very normal, neutral way to say it.

A simple pronunciation guide is:

in-SOM-ma, chee veh-DYAH-mo doh-MAH-nee ma-TEE-na in bee-blee-oh-TEH-ka

A few points:

• ci before v is pronounced like chee
• vediamo has stress on -dia-
• biblioteca has stress on -te-: biblioTEca
• insomma has stress on som

If you want to sound natural, keep the rhythm smooth:

Insomma, ci vediamo domani mattina in biblioteca.

Yes, but it does not mean exactly the same thing in every context.

• Ci vediamo domani mattina in biblioteca. = We’ll see each other tomorrow morning in the library / See you tomorrow morning in the library
• Vediamoci domani mattina in biblioteca. = Let’s meet tomorrow morning in the library

So:

• ci vediamo is more like stating or confirming the arrangement
• vediamoci is more like proposing it

That is because vediamoci is an imperative form: let’s see each other / let’s meet.

It is neutral and very common in everyday Italian.

Nothing in the sentence itself is especially formal. It works well in ordinary conversation with friends, classmates, coworkers, and many everyday situations.

If you wanted a more formal tone, you might choose different wording depending on the context, but Ci vediamo domani mattina in biblioteca is perfectly normal and polite in most situations.