L'universo contiene molte stelle.

Because il changes to l' before a singular masculine noun that begins with a vowel.

• il libro = the book
• l'universo = the universe

This is called elision. The apostrophe shows that the final vowel of the article has been dropped.

In Italian, the definite article is used more often than in English. For a general statement like this, l'universo is completely natural and expected.

So Italian says:

• L'universo contiene molte stelle.

where English says:

• The universe contains many stars.

Leaving out the article here would sound wrong in standard Italian.

Contiene is the third person singular present tense of the verb contenere.

That means it matches l'universo, which is singular:

• io contengo = I contain
• tu contieni = you contain
• lui/lei contiene = he/she/it contains

So L'universo contiene means the universe contains.

Yes, very often. Contenere can mean to contain, to hold, or to include, depending on context.

In this sentence, contiene works very much like English contains:

• L'universo contiene molte stelle.

It sounds natural and straightforward.

Because stelle is a feminine plural noun, and molto must agree with it.

The forms are:

• molto = masculine singular
• molta = feminine singular
• molti = masculine plural
• molte = feminine plural

Since stella is feminine, and here it is plural stelle, the correct form is molte.

A good clue is the ending. Many Italian nouns ending in -a in the singular are feminine.

• la stella = the star
• le stelle = the stars

So:

• singular: stella
• plural: stelle

This is a very common feminine noun pattern:

• casa → case
• porta → porte
• stella → stelle

Because many feminine nouns ending in -a form the plural by changing -a to -e.

So:

• stella = star
• stelle = stars

This is one of the most common plural patterns in Italian.

Because molte already works as a quantity word meaning many, so no article is needed here.

• molte stelle = many stars

If you added an article, it would change the meaning:

• molte stelle = many stars
• le molte stelle = the many stars

The version without the article is the normal one for this sentence.

Yes. The sentence follows a very familiar pattern:

• L'universo = subject
• contiene = verb
• molte stelle = object

So it is basically:

• The universe / contains / many stars

This makes the sentence easy for English speakers to follow.

It is pronounced roughly like loo-nee-VER-so, but with the article attached in front:

• L'universo ≈ looniverso

A few helpful points:

• the L' links directly to universo
• u is pronounced like oo
• stress falls on ver: uniVERso

So it flows as one unit: l'universo.

Yes, depending on context, molte can be translated as many or a lot of.

So molte stelle could be understood as:

• many stars
• a lot of stars

In this sentence, many stars is the most direct translation.

Yes. That means there are many stars in the universe, and it is also a natural sentence.

Compare:

• L'universo contiene molte stelle. = The universe contains many stars.
• Ci sono molte stelle nell'universo. = There are many stars in the universe.

Both are correct, but the structure is different. The original sentence is more direct and a little more formal or factual in tone.