La sessione plenaria include una tavola rotonda.

Because sessione is a feminine singular noun.

• la = the feminine singular definite article
• plenaria = the adjective plenario/plenaria, which must agree with sessione

So:

• la sessione plenaria = the plenary session

If the noun were masculine, the adjective would change too, for example:

• il dibattito plenario

In Italian, adjectives often come after the noun, much more often than in English.

So:

• sessione plenaria literally follows the pattern session plenary

That is completely normal Italian word order.
Putting the adjective before the noun is sometimes possible in Italian, but with this kind of formal descriptive adjective, after the noun is the standard position.

Include is the third person singular present of includere.

Here is the relevant part of the conjugation:

• io includo = I include
• tu includi = you include
• lui/lei include = he/she/it includes

Since the subject is la sessione plenaria = the plenary session, Italian uses include.

Yes, it is a real Italian word. It comes from the verb includere.

It looks very similar to English include because they are related words. But it is pronounced differently in Italian, roughly:

• in-KLOO-deh

So it may look familiar, but you should say it the Italian way.

Because tavola is a feminine singular noun, and here it is being introduced as a round table / round-table discussion, not the specific one.

• una = a/an for feminine singular nouns
• tavola rotonda = feminine singular noun + adjective

Compare:

• una tavola rotonda = a round-table discussion
• la tavola rotonda = the round-table discussion

It can, but in this sentence it most likely means a round-table discussion.

Literally:

• tavola = table
• rotonda = round

But in conference, academic, or business contexts, tavola rotonda is very commonly used in the figurative sense of a discussion format, like:

• a roundtable
• a panel discussion
• a round-table discussion

So here it probably does not mean that the session includes a piece of furniture.

Because rotonda is describing tavola, and tavola is feminine singular.

Italian adjectives must agree with the noun they describe:

• tavola rotonda = feminine singular
• tavolo rotondo = masculine singular

So:

• una tavola rotonda = a round table / round-table discussion
• un tavolo rotondo = a round table

Yes, depending on the nuance.

• include = includes
• comprende = includes / comprises
• prevede = includes, provides for, features, has scheduled

In event-program language, prevede is also very common. For example:

• La sessione plenaria prevede una tavola rotonda.

That can sound very natural when talking about what is on the schedule.
Still, include is perfectly understandable and correct.

Not in normal standard Italian prose.

Italian usually wants the articles here:

• La sessione plenaria include una tavola rotonda.

Leaving them out would sound unnatural in a full sentence, though article omission can happen in:

• headlines
• notes
• bullet points
• titles

So for normal speaking and writing, keep la and una.

A simple approximation is:

lah sess-YO-neh pleh-NAH-ryah een-KLOO-deh OO-nah TAH-voh-lah roh-TON-dah

A few useful stress points:

• sessióne
• plenària
• inclùde
• rotónda

If you want to sound more natural, make sure you do not pronounce include like English in-KLOOD. In Italian, the final vowel is pronounced clearly: in-KLOO-deh.