La legoma supo odoras bone.

Because legoma is the adjective form of legomo (vegetable).

• legomo = a vegetable
• legoma = vegetable / made of vegetables / relating to vegetables

In Esperanto, when one noun describes another the way an English adjective does, you usually turn it into an adjective with -a:

• frukto = fruit → frukta suko = fruit juice
• legomo = vegetable → legoma supo = vegetable soup

So legoma supo literally means vegetable-type soup or soup made from vegetables.

Yes. Esperanto often allows compounds, so legomsupo is also possible.

• legoma supo = vegetable soup
• legomsupo = vegetable soup

Both are understandable. In many cases, the two-word version with an adjective feels a bit clearer for learners, while the compound can feel a bit more compact or lexicalized. You may see both in real Esperanto.

The ending -as marks the present tense in Esperanto.

So:

• odoras = smells / is smelling

The verb is based on odori = to smell. Esperanto verb endings are regular:

• -as = present
• -is = past
• -os = future
• -us = conditional
• -u = command/jussive
• -i = infinitive

Examples:

• La supo odoras bone. = The soup smells good.
• La supo odoris bone. = The soup smelled good.
• La supo odoros bone. = The soup will smell good.

Because bone is an adverb, and here it modifies the verb odoras.

• bona = good (adjective, used with nouns)
• bone = well / in a good way (adverb, used with verbs, adjectives, or other adverbs)

In this sentence, the soup is not being directly described as good; rather, its smell is good. So Esperanto uses the adverb:

• La supo odoras bone. = The soup smells good.

Compare:

• La supo estas bona. = The soup is good.
• La supo odoras bone. = The soup smells good.

This is similar to careful English grammar, where smells good is standard, not smells well.

Usually odori means to have a smell / to give off an odor.

So in this sentence:

• La legoma supo odoras bone. means
• The vegetable soup smells good
  that is, it gives off a pleasant smell.

If you want to talk about using your nose to notice a smell, Esperanto often uses a different wording, such as:

• flari = to sniff / smell intentionally
• senti odoron = to smell, to perceive a smell

So:

• Mi flaras la supon. = I am smelling/sniffing the soup.
• Mi sentas bonan odoron. = I smell a good smell.

Because there is no direct object here.

In Esperanto, -n marks the accusative, which is commonly used for the direct object. But in this sentence:

• La legoma supo is the subject
• odoras is the verb
• bone is an adverb

Nothing is receiving the action as a direct object, so no accusative is needed.

Compare:

• La legoma supo odoras bone. = The vegetable soup smells good.
• Mi manĝas la legoman supon. = I eat the vegetable soup.

In the second sentence, la legoman supon gets -n because it is the direct object.

Because la legoma supo is one noun phrase: the vegetable soup.

The article la applies to the whole phrase, not separately to each word. Esperanto works like English here:

• the vegetable soup not
• the the vegetable soup

So:

• la = the
• legoma = vegetable
• supo = soup

Together: la legoma supo.

Yes, la is the definite article and corresponds to English the.

It does not change for:

• singular/plural
• gender
• case by itself

Examples:

• la supo = the soup
• la supoj = the soups
• la supon = the soup (as direct object)
• la supojn = the soups (as direct objects)

The word la itself stays the same.

Here is the structure:

• La = the
• legoma = vegetable / made of vegetables
• supo = soup
• odoras = smells
• bone = well / nicely / good, in an adverbial sense

So literally it is something like:

• The vegetable soup smells well/nicely

But the natural English translation is:

• The vegetable soup smells good.

Yes, Esperanto word order is fairly flexible, but the normal order here is the most natural:

• La legoma supo odoras bone.

You could also say:

• Bone odoras la legoma supo.

This changes the emphasis, putting more focus on bone. But for ordinary neutral speech, the original order is best.

Because odoras is already the main verb, and it expresses the idea completely by itself.

• La legoma supo estas bona. = The vegetable soup is good.
• La legoma supo odoras bone. = The vegetable soup smells good.

These are different meanings:

• estas bona = is good in general
• odoras bone = smells good

So Esperanto does not need estas here.

Yes. They come from the same root odor-.

• odoro = smell, odor
• odori = to smell, to have a smell
• odoras = smells
• odora = odorous, having a smell
• senodora = odorless

This is a good example of Esperanto word-building: one root can produce many related words through regular endings.

It means the smell is good or pleasant, not merely noticeable or strong.

If you wanted to say the soup smells strongly, you would use a different word, such as:

• La supo odoras forte. = The soup smells strongly.

So bone here expresses a positive judgment about the smell.

Yes, that is possible.

• bonodori = to smell good
• La legoma supo bonodoras. = The vegetable soup smells good.

This is a compact form built from:

• bon- = good
• odor- = smell
• -i = infinitive verb ending

However, odoras bone is often easier for learners to understand because it is more transparently built from common pieces.

You would make the noun and its adjective plural with -j:

• La legomaj supoj odoras bone. = The vegetable soups smell good.

Notice:

• legoma → legomaj
• supo → supoj

The adjective agrees with the noun in number.

The noun phrase would take -n, and the adjective would agree with it.

For example:

• Mi manĝas la legoman supon. = I am eating the vegetable soup.

Here:

• legoma → legoman
• supo → supon

Adjectives agree with nouns in Esperanto for:

• number (-j)
• accusative (-n)

So if a noun gets -n, its adjective gets -n too.