La tacca e lo svaso sono appigli diversi.

Because svaso begins with s + consonant (sv-), and masculine singular nouns with that pattern normally take lo in the definite article:

• lo svaso
• lo studente
• lo sport

Italian uses lo before masculine singular nouns beginning with s + consonant, z, ps, gn, and a few other sound patterns.

Italian nouns have grammatical gender, so each noun has to match the correct article.

• tacca is feminine singular → la tacca
• svaso is masculine singular → lo svaso

The endings help a little:

• nouns ending in -a are often feminine
• nouns ending in -o are often masculine

But the article is what clearly shows the gender in the sentence.

Because the subject is two things joined by e:

La tacca e lo svaso = the notch and the flare

Two singular nouns joined by e make a plural subject, so the verb must be plural:

• è = is
• sono = are

So La tacca e lo svaso sono... means The notch and the flare are...

Here appigli is a predicate noun after sono. In Italian, when you say what something is, the noun often appears without an article, especially in a general or classifying statement.

So:

• sono appigli diversi = they are different holds

This sounds natural and neutral.

If you added an article, the meaning or tone would shift. For example, sono degli appigli diversi is possible in some contexts, but it is less direct and less natural here.

Because the adjective diversi has to agree with appigli.

• appiglio = masculine singular
• appigli = masculine plural

So the adjective must also be masculine plural:

• appiglio diverso
• appigli diversi

It is not agreeing with tacca alone or svaso alone. It is agreeing with appigli, the noun it describes.

With diverso, word order can change the meaning.

• appigli diversi usually means different/distinct holds
• diversi appigli often means several/various holds

So in this sentence, appigli diversi is the right choice because the idea is that the notch and the flare are two distinct kinds of holds, not just various holds.

This is a very common and useful adjective-position difference in Italian.

Yes. In normal Italian, when you join two separate nouns with e, each noun usually keeps its own article:

• la tacca e lo svaso

That is the standard pattern here. You cannot say la tacca e svaso.

Repeating the article makes it clear that you are talking about two separate items.

Yes. The singular is appiglio, and the plural is appigli.

So the pattern is:

• un appiglio
• due appigli

This is a regular plural for a masculine noun ending in -o.

A rough guide is:

• tacca → TAK-ka
• svaso → roughly ZVA-so or SVA-so, depending on accent/region
• appigli → roughly ap-PEE-lyi, though the gli sound is a special Italian sound that does not exist exactly in English

A few useful details:

• In tacca, the cc is pronounced like a strong k sound: tak-ka
• In appigli, the gli is the same sound you hear in words like famiglia and figlio

Yes, absolutely.

Adding due makes the sentence more explicit:

• sono appigli diversi = they are different holds
• sono due appigli diversi = they are two different holds

Both are grammatical. The version without due is a little more compact and still perfectly natural.