Mi ne povas esprimi tion.

A word-for-word breakdown is:

• mi = I
• ne = not
• povas = can / am able to
• esprimi = to express
• tion = that / that thing

So the structure is very close to English: I not can express that, which natural English translates as I cannot express that or I can’t express that.

In Esperanto, ne normally goes directly before the word it negates.

Here, it negates povas, so:

• Mi ne povas esprimi tion = I cannot express that

This is the most normal way to say it.

A useful comparison:

• Mi ne povas iri = I can’t go
• Mi povas ne iri = I can choose not to go / I may be able not to go

So ne povas and povas ne do not mean the same thing.

The ending -as is the present-tense verb ending in Esperanto.

So:

• povas = can / am able to
• literally, it comes from povi = to be able to

Esperanto verbs do not change by person, so the same form is used with all subjects:

• mi povas = I can
• vi povas = you can
• li/ŝi/ĝi povas = he/she/it can
• ni povas = we can
• ili povas = they can

That is much simpler than English.

After a verb like povi (to be able to), the next verb stays in the infinitive.

So:

• Mi povas esprimi tion = I can express that
• not Mi povas esprimas tion

This works like English can express, not can expresses.

A few similar examples:

• Mi volas iri = I want to go
• Mi devas labori = I must work
• Mi povas kompreni = I can understand

Tion means that, that thing, or sometimes that idea / that situation, depending on context.

It comes from the correlative tio = that.

Then the -n ending is added:

• tio = that
• tion = that, as the direct object

So in this sentence, tion is the thing being expressed.

The -n marks the direct object in Esperanto.

In this sentence, the direct object is the thing being expressed, so tio becomes tion:

• Mi esprimas tion = I express that
• Mi ne povas esprimi tion = I cannot express that

This -n ending is very important in Esperanto because it shows what receives the action.

No. That would be ungrammatical in standard Esperanto.

Because tio is the direct object of esprimi, it must take -n:

• correct: Mi ne povas esprimi tion
• incorrect: Mi ne povas esprimi tio

A good habit is to ask: What is being expressed?
Answer: that.
So that is the object, and it needs -n.

The normal word order is:

• Mi ne povas esprimi tion

But Esperanto allows some flexibility because the grammar endings show the roles clearly.

For example, you may also see:

• Tion mi ne povas esprimi = That I cannot express
• Mi tion ne povas esprimi = also possible, with extra focus on tion

Even so, the most neutral and beginner-friendly version is the original one: Mi ne povas esprimi tion.

This is a very useful distinction.

• diri = to say
• esprimi = to express

So esprimi is often broader and more emotional or abstract. It can mean putting something into words, but also conveying a feeling, idea, or experience.

Compare:

• Mi ne povas diri tion = I can’t say that
• Mi ne povas esprimi tion = I can’t express that

The second sentence often suggests that the speaker cannot adequately put something into words.

In Esperanto, the infinitive is shown by the ending -i, so no separate word like English to is needed.

That means:

• esprimi already means to express
• povi already means to be able to

So Esperanto says:

• Mi povas esprimi tion

not something like Mi povas to esprimi tion.

The -i ending itself carries the infinitive meaning.

Sometimes yes, but the meaning is slightly different.

• tion = that / that thing / that matter
• ĝin = it

So if the context already clearly identifies a specific thing, ĝin may work:

• Mi ne povas esprimi ĝin = I can’t express it

But tion points more directly to that specific idea, situation, or thing, often something just mentioned or indicated.

Only the finite verb changes tense here. The infinitive esprimi stays the same.

Examples:

• Mi ne povas esprimi tion = I cannot express that
• Mi ne povis esprimi tion = I could not express that
• Mi ne povos esprimi tion = I will not be able to express that

This is a nice feature of Esperanto: tense is simple and regular.

A simple approximate pronunciation is:

Mee neh POH-vas es-PREE-mee TEE-on

A few helpful points:

• mi sounds like mee
• ne sounds like neh
• povas has stress on PO
• esprimi has stress on PRI
• tion is usually pronounced as two syllables, roughly TEE-on

In Esperanto, the stress is normally on the second-to-last syllable, which helps a lot with pronunciation.