Mi prenas mezuron de la maniko.

The -n marks the direct object.

• Mi prenas = I take
• What am I taking? mezuron = a measurement

So mezuro becomes mezuron because it is the thing affected by the verb.

De usually means of, from, or shows a relationship between two nouns.

Here, mezuron de la maniko means a measurement of the sleeve.

It works much like English of:

• la koloro de la ĉemizo = the color of the shirt
• la longo de la maniko = the length of the sleeve

So de la maniko tells us what the measurement is related to.

La is the definite article, meaning the.

In this sentence, la maniko suggests a specific sleeve that is already understood from the situation, such as the sleeve of a garment being measured.

Esperanto uses la much like English the. If the sleeve were not specific, the speaker might omit it, but in practical contexts like tailoring, a specific sleeve is often meant.

Esperanto has no indefinite article. There is no separate word for a or an.

So:

• mezuro can mean a measurement or just measurement
• la mezuro means the measurement

That is why mezuron by itself can naturally mean a measurement.

Yes. It is a natural way to say take a measurement.

Literally:

• preni = to take
• mezuro = measurement

So preni mezuron de... is similar to English to take a measurement of...

Depending on context, Esperanto speakers might also use other phrasing, but this expression is understandable and normal.

Yes. Mi mezuras la manikon means I am measuring the sleeve and is also very natural.

There is a slight difference in feel:

• Mi mezuras la manikon = I am measuring the sleeve
• Mi prenas mezuron de la maniko = I am taking a measurement of the sleeve

The second phrasing focuses a bit more on the measurement itself, while the first focuses on the action of measuring.

Maniko means sleeve, as in the sleeve of a shirt, coat, dress, and so on.

Some related forms:

• maniko = sleeve
• la maniko = the sleeve
• manikoj = sleeves
• la manikoj = the sleeves

Because the sentence refers to one measurement.

For example, it might mean:

• the sleeve length
• the width of the sleeve
• one particular measurement needed in sewing

If you meant several measurements, you would use the plural:

• Mi prenas mezurojn de la maniko = I take measurements of the sleeve

The word order here is the most neutral and common:

• Mi = subject
• prenas = verb
• mezuron = object
• de la maniko = phrase modifying mezuron

Esperanto word order is fairly flexible because the endings show the grammar, but Mi prenas mezuron de la maniko is the clearest default order.

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

So:

• Mi = one syllable
• prenas → PRE-nas
• mezuron → me-ZU-ron
• de = one syllable
• la = one syllable
• maniko → ma-NI-ko

So the sentence is pronounced roughly:

Mi PREnas meZUron de la maNIko