Ni konstruis malgrandan muron.

Esperanto makes this very regular by using endings:

• ni = pronoun
• konstru-is = verb in the past tense
• malgrand-a-n = adjective
• mur-o-n = noun

Some very important endings here are:

• -o = noun
• -a = adjective
• -is = past-tense verb
• -n = accusative ending, usually marking the direct object

So even before you know all the vocabulary, the endings tell you a lot about the grammar.

Because -is is the Esperanto ending for the past tense.

So:

• konstrui = to build
• konstruas = build / is building / are building
• konstruis = built
• konstruos = will build

The root is konstru-, and the tense ending tells you when the action happened. Esperanto verbs do not change for person, so:

• mi konstruis
• vi konstruis
• li konstruis
• ni konstruis

all use the same past-tense ending -is.

The -n marks the direct object.

In this sentence, muron is the thing that was built, so it gets -n.

• muro = wall
• muron = wall as the direct object

This is called the accusative ending.

Compare:

• La muro falis. = The wall fell.
  Here muro is the subject, so no -n.
• Ni konstruis muron. = We built a wall.
  Here muron is the object, so it takes -n.

Because adjectives in Esperanto agree with the nouns they describe.

Since muron is:

• singular
• accusative

the adjective describing it must match:

• malgranda muro = a small wall
• malgrandan muron = a small wall as the direct object

So malgrandan has:

• -a because it is an adjective
• -n because it describes an accusative noun

This agreement is a very common feature of Esperanto.

It can be broken down like this:

• mal- = opposite
• grand = big
• -a = adjective
• -n = accusative

So:

• granda = big
• malgranda = small
• malgrandan = small, with accusative agreement

A very common Esperanto pattern is using mal- to form opposites:

• bona = good → malbona = bad
• fermi = close → malfermi = open
• granda = big → malgranda = small

Because Esperanto often uses the prefix mal- to make the opposite of a word.

Instead of needing completely separate unrelated words for big and small, Esperanto can use:

• granda = big
• malgranda = small

That said, Esperanto sometimes also has other words with similar meanings. But malgranda is the normal, everyday word for small.

Esperanto usually does not use an indefinite article.

So English a small wall is simply:

• malgranda muro

Esperanto does have a definite article:

• la = the

So:

• muro = a wall / wall
• la muro = the wall

That means Ni konstruis malgrandan muron naturally expresses We built a small wall without needing a separate word for a.

Yes, more easily than in English, because the -n helps show what the object is.

The normal order is:

• Ni konstruis malgrandan muron.

But you could also say things like:

• Malgrandan muron ni konstruis.

This might sound more emphatic, like focusing on a small wall.

Even so, subject–verb–object is the most neutral and common word order, especially for learners.

You would add -j for the plural, and the adjective would still have to agree with the noun.

So:

• Ni konstruis malgrandajn murojn. = We built small walls.

Breakdown:

• mur-oj-n = walls, as direct object
• malgrand-a-j-n = small, plural, accusative

The agreement pattern is:

• -a for adjective
• -j for plural
• -n for accusative

Both the adjective and the noun show the matching grammar.

A simple approximation is:

Nee kon-STROO-iss mahl-GRAHN-dahn MOO-rohn

A few helpful points:

• ni sounds like nee
• stru in konstruis has a clear oo sound
• grand has a broad ah sound
• u in Esperanto is always like oo
• r is usually trilled or tapped, not the English r
• every letter is pronounced clearly

Also, stress in Esperanto usually falls on the second-to-last syllable:

• kon-STRU-is
• mal-GRAN-dan
• MU-ron