Tăiem un metru de cablu.

Tăiem is the 1st person plural present tense of the verb a tăia, meaning to cut.

So:

• eu tai = I cut / I am cutting
• noi tăiem = we cut / we are cutting

In this sentence, tăiem means we cut or we are cutting, depending on context.

Romanian often drops subject pronouns when they are not needed, because the verb ending already shows who the subject is.

Here, -em in tăiem tells you the subject is we.

So:

• Tăiem un metru de cablu. = We cut / We are cutting one meter of cable.
• Noi tăiem un metru de cablu. also works, but noi is usually added only for emphasis or contrast.

It can mean either one. Romanian present tense often covers both:

• a habitual meaning: we cut
• an ongoing meaning: we are cutting

The context tells you which one is intended.

Un here means one and also functions like a/an, depending on how you think about it.

In un metru, it is best understood as the numeral one in a measurement phrase:

• un metru = one meter

Romanian uses the same word un for:

• the masculine/neuter indefinite article: a/an
• the numeral one

Because the quantity is one meter, Romanian uses the singular:

• un metru = one meter
• doi metri = two meters

So the noun after one stays singular, just as in English.

In Romanian, after a measure expression, you often use de before the material or substance being measured.

So:

• un metru de cablu = one meter of cable
• doi litri de apă = two liters of water
• un kilogram de făină = one kilogram of flour

Here, de cablu means of cable.

De is used for quantity/measure:

• un metru de cablu = one meter of cable

Din usually means from/out of and would suggest cutting something from a specific cable:

• Tăiem un metru din cablu. = We cut one meter off the cable / from the cable

So:

• de cablu = a measured amount of cable
• din cablu = taken from a particular cable

Because the phrase refers to cable as a quantity/material, not the cable as a specific identified object.

Compare:

• un metru de cablu = one meter of cable
• un metru din cablul acesta = one meter from this cable

After measure expressions, Romanian normally uses the indefinite base form of the noun:

• de apă
• de lemn
• de cablu

After de, Romanian traditionally treats the noun as part of a prepositional construction, often corresponding to a genitive-like or partitive meaning in English.

In practice, for a learner, the important point is simpler:

• after measure words, Romanian often uses de + noun
• the noun usually appears in its basic indefinite form

So you do not need to think of cablu here as changing visibly for case.

The dictionary form is a tăia, meaning to cut.

This is a common Romanian verb. Its present forms include:

• eu tai
• tu tai
• el/ea taie
• noi tăiem
• voi tăiați
• ei/ele taie

So tăiem belongs to the verb a tăia.

Roughly: tuh-YEM, but with Romanian sounds.

A few pronunciation notes:

• ă is a short central vowel, like the sound in the second syllable of sofa
• ie in tăiem forms part of the next syllable
• stress is on the second syllable: tă-IEM

And:

• metru is roughly MEH-troo
• cablu is roughly KAH-bloo

Yes. Romanian word order is fairly flexible, although Tăiem un metru de cablu is the most neutral order.

You may also hear:

• Un metru de cablu tăiem. = more marked, often emphasizing the object
• Noi tăiem un metru de cablu. = emphasizes we

But for normal, neutral usage, Tăiem un metru de cablu is the best pattern to learn first.

Cablu is a neuter noun in Romanian.

That means:

• in the singular, it behaves like a masculine
• in the plural, it behaves like a feminine

So:

• singular: un cablu
• plural: două cabluri

In this sentence, that is why you see un metru de cablu, not o.