Il tacco scollato è riparabile.

Because tacco starts with a normal consonant sound: t.

In Italian:

• il is used before most masculine singular nouns: il tacco
• lo is used before masculine singular nouns beginning with s + consonant, z, ps, gn, x, and a few others: lo studente, lo zaino

So il tacco is the correct form.

Here tacco means the heel of a shoe.

Italian tacco can also mean heel in a more general sense, but in this sentence the context is clearly footwear, because scollato suggests that the heel has come loose from the shoe.

So il tacco here is not the heel of a foot; it is the shoe heel.

Here scollato means something like unglued, come unstuck, or detached because the glue has loosened.

It comes from the verb scollare, which can mean to unglue, to detach, or to come unstuck.

So a tacco scollato is a heel that has come loose from the shoe.

A useful warning: scollato can also mean low-cut or décolleté when talking about clothing, especially necklines. But that is not the meaning here.

Because in Italian, adjectives often come after the noun.

So:

• il tacco scollato = the detached/unglued heel

Putting the adjective after the noun is the normal, unmarked order here.

If you moved it before the noun, it would sound unusual or stylistically marked in this case. For this kind of descriptive adjective, post-noun position is the natural choice.

Because it agrees with tacco, which is:

• masculine
• singular

In Italian, adjectives must agree with the noun they describe.

So you get:

• il tacco scollato — masculine singular
• la scarpa scollata — feminine singular
• i tacchi scollati — masculine plural
• le scarpe scollate — feminine plural

The -o ending shows masculine singular agreement.

It is originally the past participle of scollare, but here it is being used as an adjective.

That is very common in Italian. Many past participles function like adjectives:

• una porta chiusa = a closed door
• un vetro rotto = a broken glass/pane
• un tacco scollato = a detached/unglued heel

So grammatically, you can think of scollato here as a descriptive adjective derived from a verb.

Riparabile is an adjective meaning repairable.

It comes from the verb riparare + the suffix -abile, which often means able to be ...-ed.

Examples:

• lavare → lavabile = washable
• leggere → leggibile = readable
• riparare → riparabile = repairable

So è riparabile means is repairable or can be repaired.

This is an important difference:

• riparabile = repairable, able to be repaired
• riparato = repaired, already fixed

So:

• Il tacco scollato è riparabile = the detached heel can be repaired
• Il tacco è riparato = the heel has been repaired / is repaired

One describes possibility; the other describes a completed result.

Both are possible, but they are slightly different in style.

• è riparabile is more compact and adjective-based: it is repairable
• si può riparare is more verbal and often a bit more conversational: it can be repaired

So:

• Il tacco scollato è riparabile sounds like a statement about the item's condition or repairability.
• Il tacco scollato si può riparare sounds slightly more like saying that repairing it is possible.

In many contexts, they are very close in meaning.

Because è is the third-person singular of essere: is.

The accent distinguishes it from e, which means and.

So:

• è = is
• e = and

This accent is mandatory in normal writing.

Yes. Double consonants matter a lot in Italian pronunciation and sometimes in meaning.

In scollato, the ll is pronounced more strongly/longer than a single l. Native speakers hear that difference.

This is one of the features English speakers often need to pay attention to, because English usually does not treat doubled consonants the same way Italian does.

So when you say scollato, try not to reduce it to something like a single-l pronunciation.