L'ala è piccola.

Because la becomes l' before a word that starts with a vowel. This is called elision.

So:

• la + ala → l'ala

The noun is still feminine singular; the apostrophe only shows that the a of la has been dropped.

Yes. Ala is a feminine singular noun.

That is why it uses:

• the feminine article la / l'
• the feminine singular adjective piccola

So the grammar matches all the way through:

• l'ala = feminine singular
• è piccola = feminine singular adjective

Because Italian adjectives usually agree with the noun they describe in gender and number.

Since ala is feminine singular, the adjective must also be feminine singular:

• piccolo = masculine singular
• piccola = feminine singular
• piccoli = masculine plural
• piccole = feminine plural

So L'ala è piccola uses piccola because ala is feminine singular.

Because è is the verb essere in the third person singular: is.

The accent is important because it distinguishes è from e:

• è = is
• e = and

So the accent is not optional here.

Normally, no. In standard Italian, a singular countable noun like ala usually needs an article in a sentence like this.

So the normal form is:

• L'ala è piccola.

Leaving out the article would sound incomplete or unnatural in most contexts.

A rough English-friendly pronunciation is:

LAH-lah eh PEEK-ko-lah

A few details:

• l'ala sounds like LAH-lah
• è sounds like eh
• piccola sounds like PEEK-ko-lah
• the cc in piccola has a hard k sound

Italian pronunciation is usually very regular, so once you know the sound rules, this sentence is quite straightforward.

The normal, neutral order is:

• L'ala è piccola.

This is the standard subject + verb + adjective pattern.

You may see other orders in special contexts, but they are usually more literary, emphatic, or less natural for a beginner. For example:

• Piccola è l'ala sounds marked or poetic, not the normal everyday order.

Also, note the difference between a sentence and a noun phrase:

• L'ala è piccola = full sentence
• la piccola ala = the small wing (noun phrase, not a full sentence)

The plural of ala is ali.

So the plural sentence would be:

• Le ali sono piccole.

Notice all the changes:

• l'ala → le ali
• è → sono
• piccola → piccole

That is another good example of agreement in Italian.