Haec pira suaviora sunt quam illa.

Because pirum is a neuter second-declension noun, not a first-declension feminine noun.

Its basic forms are:

• singular: pirum = pear
• plural: pira = pears

A very important Latin pattern is:

• neuter plural nominative/accusative often ends in -a

So even though -a often looks singular to an English-speaking learner, here it is definitely plural.

Because pira is neuter plural, and haec is the nominative neuter plural form of hic, haec, hoc.

The demonstrative has to agree with the noun in:

• gender
• number
• case

So:

• hae = feminine nominative plural
• haec = neuter nominative plural

Since pira is neuter plural, Latin uses haec pira = these pears.

Here haec is:

• nominative plural
• neuter
• modifying pira

That matters because haec can represent more than one grammatical form in Latin. In this sentence, the noun pira tells you which one it must be.

So haec here means these, agreeing with pira.

Suaviora is the comparative form of suavis.

The positive adjective is:

• suavis = sweet, pleasant

The comparative stem is:

• suavior- = sweeter

Then it takes endings that match the noun it describes. Since pira is neuter plural nominative, the correct form is:

• suaviora = sweeter

A useful pattern:

• masculine/feminine singular: suavior
• neuter singular: suavius
• masculine/feminine plural: suaviores
• neuter plural: suaviora

Usually Latin builds the idea of more directly into the adjective itself.

So instead of something like more sweet, Latin normally says:

• suavis = sweet
• suavior / suaviora = sweeter

This is similar to English sweet → sweeter, rather than more sweet.

Because the subject is plural:

• haec pira = these pears

Since pira is plural, the verb must also be plural:

• sunt = are

So:

• haec pira ... sunt = these pears are ...

Because Latin often leaves out a noun when it is obvious from context.

Here illa literally means those, and the omitted noun is understood:

• illa (pira) = those pears

English can do the same thing:

• These pears are sweeter than those.

You do not have to repeat pears if the meaning is already clear.

Because with quam in a comparison, the second item normally appears in the same case as the first item it is being compared with.

Here the comparison is between:

• haec pira = these pears
• illa (pira) = those pears

The first item is nominative, since it is the subject. Therefore the second item is also nominative after quam:

• quam illa = than those

Quam introduces the second half of a comparison: than.

So the structure is:

• haec pira = these pears
• suaviora sunt = are sweeter
• quam illa = than those

Together:

• These pears are sweeter than those.

With comparatives, Latin often uses:

• comparative adjective + quam + same case

That is exactly what is happening here.

Sometimes yes. Latin can also use the ablative of comparison instead of quam.

But with a pronoun like illa, using quam is very natural and very clear for learners.

So this sentence uses the straightforward pattern:

• suaviora ... quam illa

That is an excellent model to remember.

It is fairly natural, but Latin word order is more flexible than English word order.

The sentence is:

• Haec pira suaviora sunt quam illa.

Latin puts the words in this order:

• Haec pira = these pears
• suaviora = sweeter
• sunt = are
• quam illa = than those

English requires a stricter order, but Latin can often rearrange elements for emphasis. Even so, the agreement of endings tells you what goes with what.

Because the endings match.

Both are:

• neuter
• plural
• nominative

So:

• pira = neuter plural nominative
• suaviora = neuter plural nominative

Latin adjectives agree with the nouns they describe in:

• gender
• number
• case

That agreement is what links suaviora to pira.

By itself, illa could refer to those things in a general sense. But in this sentence, the context strongly points to those pears.

Latin often omits repeated nouns, so the listener is expected to understand:

• quam illa (pira)

So while illa is grammatically broad enough to mean those things, the sentence clearly means those pears.