La pronuncia di “gli” mi sembra difficile, quindi la ascolto due volte.

No. Here gli is not the masculine plural article/pronoun. It is being mentioned as a sound/spelling itself.

In La pronuncia di gli mi sembra difficile, the speaker is talking about how to pronounce the sequence gli, not using gli as a normal grammatical word.

That is why it is set off typographically in the original sentence: it is being treated like a word or sound under discussion.

This is one of the sounds English speakers often find tricky.

A rough guide:

• gli is often pronounced something like lyi
• but it is not exactly the English lee or yee
• the tongue needs to be raised toward the roof of the mouth

A common approximation is to compare it to the lli sound in English million, but Italian usually makes it cleaner and more distinct.

So gli is roughly:

• /ʎi/ in many cases

Examples:

• gli = that special sound by itself
• famiglia = the gli there has the same core sound

English speakers often need practice hearing and repeating it, so the sentence is very natural.

Because di means of here.

• la pronuncia = the pronunciation
• di gli = of gli

So the structure is simply:

• la pronuncia di X = the pronunciation of X

You could use the same pattern with other sounds or words:

• la pronuncia di ciao
• la pronuncia di gn
• la pronuncia di questo nome

Because mi sembra difficile means it seems difficult to me.

Breakdown:

• mi = to me
• sembra = seems
• difficile = difficult

So:

• Mi sembra difficile = It seems difficult to me

This is a little softer and more personal than è difficile:

• È difficile = It is difficult
• Mi sembra difficile = It seems difficult to me / I find it difficult

Italian uses sembrare very often for giving impressions or opinions.

Mi is an indirect object pronoun meaning to me.

So:

• mi sembra = it seems to me
• ti sembra = it seems to you
• gli sembra = it seems to him
• ci sembra = it seems to us

It does not mean me as a direct object here. It means to me.

La is a direct object pronoun meaning it, and it refers back to la pronuncia.

Because pronuncia is feminine singular, the pronoun is also feminine singular:

• la pronuncia → la
• la ascolto = I listen to it

So the second part means:

• quindi la ascolto due volte = so I listen to it twice

In natural English, we might say I listen to it twice or I listen to it two times.

Because in Italian, unstressed direct object pronouns usually come before a conjugated verb.

So:

• ascolto la pronuncia = I listen to the pronunciation
• la ascolto = I listen to it

This is normal Italian word order.

Compare:

• Leggo il libro → Lo leggo
• Compro la mela → La compro
• Ascolto la pronuncia → La ascolto

Because ascoltare usually means to listen, while sentire usually means to hear or to feel/perceive.

Here the speaker is intentionally listening to the pronunciation for practice, so ascoltare is the better verb.

• ascoltare = to listen to
• sentire = to hear

So:

• la ascolto due volte = I listen to it twice not
• I hear it twice

Quindi means so, therefore, or thus.

It links the two ideas:

• the pronunciation seems difficult
• as a result, the speaker listens to it twice

So the logic is:

• Mi sembra difficile, quindi la ascolto due volte
• It seems difficult to me, so I listen to it twice

Italian often uses due volte for twice.

Literally:

• due = two
• volte = times

So:

• una volta = once / one time
• due volte = twice / two times
• tre volte = three times

Italian does have una volta and due volte, but there is no everyday single-word equivalent exactly like English twice that is used more commonly than due volte.

Yes. Before a vowel, la is often elided to l':

• la ascolto
• l'ascolto

Both are possible, but l'ascolto is often smoother and more natural in writing and speech.

Be careful not to confuse this with the noun l'ascolto meaning listening or the act of listening. In this sentence, it is clearly:

• l' = pronoun la
• ascolto = verb I listen

Yes. A few natural alternatives are:

• La pronuncia di gli mi sembra difficile, perciò la ascolto due volte.
• La pronuncia di gli è difficile per me, quindi la ascolto due volte.
• Poiché la pronuncia di gli mi sembra difficile, la ascolto due volte.

The original sentence is already correct and natural. It clearly expresses:

1. a personal impression: mi sembra difficile
2. a consequence: quindi
3. a repeated action for practice: la ascolto due volte