Hoc consilium utilius est quam illud.

Because consilium is a neuter noun.

The demonstrative hic, haec, hoc means this, but it changes form to match the noun’s gender, number, and case. Since consilium is neuter singular nominative here, the correct form is hoc.

So:

• hic = masculine
• haec = feminine
• hoc = neuter

Because consilium is neuter, Latin says hoc consilium = this plan.

It is nominative singular.

This is because hoc consilium is the subject of the sentence, and the verb est means is.

So the basic structure is:

• hoc consilium = subject
• utilius = predicate adjective/complement
• est = is
• quam illud = than that

Since the subject is singular, the verb is also singular: est.

Consilium can mean several related things, depending on context:

• plan
• decision
• advice
• strategy
• purpose

In this sentence, it most naturally means plan or course of action.

That is common in Latin: one word often covers a wider range of meanings than a single English word does.

Because utilius is the neuter nominative singular form of the comparative adjective.

The adjective is utilis = useful. Its comparative is:

• masculine/feminine: utilior = more useful
• neuter: utilius = more useful

Since consilium is neuter, the comparative adjective must also be neuter:

• consilium utilius = a more useful plan

So utilius agrees with consilium.

The pattern is:

[thing 1] + comparative adjective + est + quam + [thing 2]

So here:

• hoc consilium = this plan
• utilius = more useful
• est = is
• quam illud = than that

Together:

Hoc consilium utilius est quam illud.
= This plan is more useful than that one.

Latin comparatives are often very similar in function to English comparatives.

Because Latin often omits a noun when it is easy to understand from context.

Here, illud really means that one, and the full idea is:

quam illud consilium = than that plan

But since consilium was already mentioned, Latin leaves it out.

This is called ellipsis. English does the same thing:

• This plan is better than that one
• not necessarily better than that plan

So illud stands in for illud consilium.

It is nominative singular neuter.

With quam in a comparison like this, the second item is normally put in the same case as the first item.

Since hoc consilium is nominative, illud is also nominative.

So the comparison is:

• hoc consilium = nominative
• illud = nominative

You can think of it as:

This plan is more useful than that plan is.

That is why the matching nominative makes sense.

In comparative sentences like this, yes, quam means than.

So:

• utilius quam illud = more useful than that

But quam can also appear in other expressions, especially with words like tam ... quam = as ... as.

For this sentence, though, the important thing is simply:

• comparative + quam = more/less ... than

Sometimes Latin can make a comparison without quam, using the ablative of comparison instead. But in this sentence, quam is the normal and clear way to express the comparison.

For example, Latin sometimes says things like:

• Marco altior est = he is taller than Marcus

But with pronouns like illud, using quam is especially natural and straightforward:

• utilius est quam illud

So for a learner, this sentence is a very standard model of comparison.

Here it is an adjective, not an adverb.

Why?

Because it describes consilium, the noun:

• consilium = plan
• utilius = more useful

So the meaning is this plan is more useful.

It happens that the neuter comparative form can also look like an adverb in other contexts, but here the grammar shows it is an adjective:

• it goes with consilium
• it is part of the predicate with est

No. Latin word order is fairly flexible.

This sentence could appear in other orders and still mean the same basic thing, because the endings show the grammatical relationships:

• Hoc consilium utilius est quam illud
• Hoc consilium quam illud utilius est
• Utilius est hoc consilium quam illud

These can differ slightly in emphasis, but not in core meaning.

The given order is very natural and clear.

Sometimes, yes. Latin often leaves out forms of esse (to be) when they are easy to understand.

So in some contexts you might see:

Hoc consilium utilius quam illud.

But in a basic teaching sentence, est is usually included because it makes the structure clearer.

So:

• with est = fully expressed
• without est = possible in Latin, especially in certain styles

Because Latin usually builds the idea of more X directly into the adjective itself.

Instead of saying:

• more useful

Latin says:

• utilius

This is the comparative form of utilis.

So:

• utilis = useful
• utilior / utilius = more useful

This is similar to English words like:

• big → bigger
• small → smaller

Latin just does this with many adjectives.