La kato gratas la seĝon.

La is the definite article, meaning the.

It appears twice because Esperanto uses la separately before each definite noun, just as English often does:

• la kato = the cat
• la seĝon = the chair

So the sentence has two definite nouns, and each one gets its own la.

Esperanto has no indefinite article. That means there is a word for the (la), but no separate word for a/an.

So:

• kato can mean a cat or just cat, depending on context
• la kato means the cat

In this sentence, the speaker chose la, so both the cat and the chair are presented as specific.

The -n is the accusative ending. It marks the direct object of the verb: the thing receiving the action.

Here:

• la kato does the scratching
• la seĝon receives the scratching

So seĝo becomes seĝon because it is the direct object.

This is one of the most important endings in Esperanto.

Because la kato is the subject, not the direct object.

In this sentence:

• la kato = the one doing the action
• la seĝon = the thing being acted on

Only the direct object gets -n here, so:

• kato stays kato
• seĝo becomes seĝon

-as is the Esperanto ending for the present tense.

So gratas means that the action is happening in the present:

• gratas = scratches / is scratching

Esperanto verb endings are very regular:

• -as = present
• -is = past
• -os = future
• -us = conditional
• -u = command or wish
• -i = infinitive

So the dictionary form is grati, and gratas is the present-tense form.

No. In Esperanto, the verb does not change according to person or number.

So you get:

• mi gratas = I scratch
• vi gratas = you scratch
• la kato gratas = the cat scratches
• ili gratas = they scratch

The ending -as stays the same for all subjects. This is much simpler than English.

Yes, Esperanto word order is fairly flexible, because the -n ending helps show what is the object.

The normal, most neutral order is:

• La kato gratas la seĝon.

But you could also say:

• La seĝon gratas la kato.

That still means the cat is scratching the chair, because seĝon still has the object marker -n.

Even so, subject–verb–object is the most common and natural order for beginners.

Ĝ is pronounced like the j in judge or jam.

So seĝo sounds roughly like SEH-jo, and seĝon like SEH-jon.

A few useful comparisons:

• g = hard g, like in go
• ĝ = soft sound like English j

So seĝo and sego would sound different.

In Esperanto, the stress is always on the second-to-last syllable.

So:

• kato → KA-to
• gratas → GRA-tas
• seĝon → SE-ĝon

This rule is extremely regular, which makes pronunciation much easier once you learn it.

Usually, kato just means cat without specifying sex.

If you want to be specific:

• katino = female cat
• virkato = male cat

So in this sentence, kato normally means simply cat, unless the context makes the sex important.

Esperanto makes plurals with -j.

So:

• kato = cat
• katoj = cats
• seĝo = chair
• seĝoj = chairs

If the direct object is plural, it takes both -j and -n:

• seĝojn = chairs, as a direct object

Examples:

• La katoj gratas la seĝon. = The cats scratch the chair.
• La kato gratas la seĝojn. = The cat scratches the chairs.
• La katoj gratas la seĝojn. = The cats scratch the chairs.

So plural and object marking can stack together.