Etichetăm cartonul cu markerul.

Etichetăm is the 1st person plural present tense of a eticheta.

So it means we label or we are labeling. Romanian often uses the simple present where English might use either the simple present or the present continuous, depending on context.

Romanian usually does not need a subject pronoun if the verb ending already makes the subject clear.

The ending -ăm tells you the subject is we.

So:

• Etichetăm = we label / we are labeling

You can add noi for emphasis or contrast:

• Noi etichetăm cartonul cu markerul. = We are labeling the cardboard/carton.

Because Romanian usually puts the definite article at the end of the noun.

• carton = cardboard / carton

• cartonul = the cardboard / the carton

• marker = marker
• markerul = the marker

So -ul here is the masculine/neuter singular definite article attached to the noun.

Both can be possible, but they are slightly different.

• cu markerul = with the marker, often meaning the marker being used or the one already understood from context
• cu un marker = with a marker, emphasizing that it is one marker, not necessarily a specific known one

Romanian often uses the definite article with instruments more naturally than English does. So even if English says with a marker, Romanian may still say cu markerul.

Cu usually means with.

In this sentence, it shows the instrument used to do the action:

• cu markerul = with the marker / using the marker

So the sentence tells you both:

• what is being labeled
• what tool is being used

Because cartonul is an inanimate direct object.

In Romanian, pe is often used before specific human direct objects, and sometimes other highly specific or animate ones, but normally not before ordinary inanimate things.

So:

• Etichetăm cartonul = correct
• Etichetăm pe cartonul = not correct here

Carton can mean different but related things depending on context, such as:

• cardboard
• carton
• sometimes a cardboard box/package

So cartonul means the cardboard / the carton / the box, depending on the situation. Romanian often relies on context for the most natural English equivalent.

The order in this sentence is the most neutral one:

• Etichetăm cartonul cu markerul.

That is basically:

• verb + direct object + prepositional phrase

Romanian word order is fairly flexible, though. You can move things around for emphasis, but the version given is the most straightforward and natural in many contexts.

A rough pronunciation is:

• e-ti-ke-TĂM

A few useful points:

• ch before e or i sounds like k, not like English ch
• ă is a short central vowel, somewhat like the a in about
• the stress is on the last syllable here: -tăm

So etichetăm is not pronounced like English etch-, but more like eh-tee-keh-TUHM.

Both are neuter nouns in Romanian.

That means they behave:

• like masculine in the singular
• like feminine in the plural

For example:

• un carton / două cartoane
• un marker / două markere

That is why in the singular definite form you get:

• cartonul
• markerul

It can mean either one, depending on context.

Romanian does not have a separate mandatory present continuous form like English. The simple present often covers both:

• we label
• we are labeling

So you understand the exact time sense from context, not from a special verb form here.