O secundă trece repede.

In this sentence, o is the indefinite article meaning a/an.

• o secundă = a second

Romanian uses the same form o for:

• the feminine singular indefinite article: a/an
• the number one in feminine form

So by itself, o can mean either one or a/an, but in a sentence like this it is usually understood as a.

Because secundă is a feminine noun in Romanian.

• singular: o secundă
• plural: două secunde

Many Romanian nouns have grammatical gender, and the article and other words around them often reflect that. Since secundă is feminine, it takes the feminine singular article o.

Trece is the 3rd person singular present tense of the verb a trece.

So:

• a trece = to pass
• trece = passes

In O secundă trece repede, the subject is o secundă (a second), which is singular, so the verb is also singular: trece.

Romanian often does not need an explicit subject pronoun when the subject is already stated.

Here, the subject is o secundă, so there is no need to add a separate word for it.

English says:

• A second passes quickly

Romanian says:

• O secundă trece repede

The noun itself is enough to show what is doing the action.

Repede is an adverb, and it means quickly / fast.

It modifies the verb trece:

• trece repede = passes quickly

Romanian often uses repede where English might use either quickly or fast, depending on context.

That is a very normal word order in Romanian.

• trece repede = passes quickly

Romanian adverbs often come after the verb, especially in simple, neutral sentences. That said, Romanian word order is somewhat flexible, and moving words can change emphasis.

For example:

• O secundă trece repede. = neutral
• O secundă repede trece. = unusual in ordinary speech

So the given order is the most natural one.

It can be understood as a general truth or present-time statement, depending on context.

Romanian present tense often covers both:

• general truths
• habitual actions
• present events

So this sentence can mean something like:

• A second passes quickly
• One second goes by quickly

Without context, it feels like a general observation.

A helpful approximate pronunciation is:

• o → like oh
• secundă → seh-KOON-duh
• trece → roughly TREH-che
• repede → REH-peh-deh

A few details:

• ă is a short central vowel, often approximated as uh
• ce at the end of trece is pronounced like che in check, but softer/shorter

So the whole sentence sounds approximately like:

oh seh-KOON-duh TREH-che REH-peh-deh

The dictionary form is a trece.

In Romanian, verbs are usually listed in the infinitive, and that infinitive often appears with a:

• a trece = to pass
• a merge = to go
• a vedea = to see

So a here is like English to in dictionary forms. But in a normal sentence, you use the conjugated form:

• trece, not a trece

Yes, rapid can also work in many contexts, but repede is more common and natural in everyday speech here.

Compare:

• O secundă trece repede. = very natural
• O secundă trece rapid. = understandable, slightly more formal or stylistically different

For a learner, repede is the safest everyday choice.

Yes. In this sentence, secundă is the noun meaning the time unit second.

Examples:

• o secundă = a second
• două secunde = two seconds

So the sentence is talking about time passing.

Yes, Romanian has more flexible word order than English, but not every version sounds equally natural.

The most neutral version is:

• O secundă trece repede.

You may also encounter:

• Repede trece o secundă. = more marked, with emphasis on quickly
• Trece repede o secundă. = possible in some contexts, but less neutral

For a learner, the original sentence is the best standard pattern:

• subject + verb + adverb

A trece is a very common verb with several meanings depending on context. It can mean:

• to pass: Trece timpul. = Time passes.
• to go by: O zi trece repede. = A day goes by quickly.
• to cross: Trec strada. = I cross the street.
• to move past: Trenul trece. = The train passes by.

So in this sentence, the meaning is specifically the time-passing sense.