Curățenia începe după micul dejun.

Here curățenia means the cleaning, the housework, or the cleaning-up.

Even though curățenie can also mean cleanliness in other contexts, this sentence clearly uses it for an activity:

• Curățenia începe... = The cleaning starts...

So this is not about the abstract idea of cleanliness. It is about the task or routine of cleaning.

Because Romanian is using the definite form here.

• curățenie = cleaning / cleanliness
• curățenia = the cleaning

Romanian usually puts the definite article at the end of the noun instead of using a separate word like English the.

So:

• curățenie = cleaning
• curățenia = the cleaning

In this sentence, the speaker is referring to a specific, understood activity, so curățenia is natural.

Începe is the 3rd person singular present tense of the verb a începe = to begin / to start.

So:

• a începe = to begin
• începe = begins / starts

Why 3rd person singular? Because the subject is curățenia, which is singular:

• Curățenia începe = The cleaning begins

Romanian often does not need a subject pronoun when the subject is already clear.

Here the subject is stated explicitly:

• Curățenia = the cleaning

So Romanian does not need to add ea (she/it) before the verb.

Also, Romanian verbs already show person and number, so subject pronouns are used less often than in English.

Because micul dejun is the normal form here for breakfast in a specific or routine sense, especially in a sentence like this.

English often says simply after breakfast with no article. Romanian more often uses the definite form in this kind of expression:

• după micul dejun = after breakfast

So even though English has no the, Romanian naturally does.

Micul dejun is the standard Romanian expression for breakfast.

Literally, it comes from:

• mic = small
• dejun = lunch / midday meal

Historically, it is something like small lunch, but you should really learn micul dejun as a fixed expression meaning breakfast.

The article appears on micul because Romanian can place the definite article on a preceding adjective in certain structures. In everyday learning, the easiest approach is:

• treat micul dejun as one set phrase = breakfast
• treat după micul dejun as one common chunk = after breakfast

Not visibly here.

După is a preposition, and in grammar terms it is followed by the accusative, but for nouns like this, the accusative usually looks the same as the nominative.

So:

• micul dejun stays micul dejun
• after după, there is no extra ending change here

That is why you simply get:

• după micul dejun = after breakfast

Yes. Romanian word order is fairly flexible.

The neutral order here is:

• Curățenia începe după micul dejun.

But you could also say:

• După micul dejun începe curățenia.

That still means the same thing: The cleaning starts after breakfast.

The difference is mainly focus or style:

• starting with Curățenia emphasizes the activity
• starting with După micul dejun emphasizes the time

A few sounds here are especially useful for English speakers:

• ă in Curățenia and după
  Pronounced like a short uh sound, similar to the a in sofa.

• ț in Curățenia
  Pronounced ts, like the end of English cats.

• î in începe
  This is a Romanian vowel that English does not really have. It is a tight central sound. At beginner level, just try to copy native audio rather than forcing it into an English vowel.

• ce in începe
  Pronounced che, like ch in check.

• j in dejun
  Pronounced like the s in measure or the g in genre.

A rough beginner-friendly pronunciation guide would be:

• Curățenia ≈ koo-ruh-TSEH-nee-ah
• începe ≈ in-CHEH-peh (very approximate)
• după ≈ DOO-puh
• micul dejun ≈ MEE-kool de-ZHOON

Yes, absolutely.

• începe = begins / starts

Both are correct in English.
So the sentence can be understood as either:

• The cleaning begins after breakfast.
• The cleaning starts after breakfast.

Starts usually sounds a bit more natural in everyday English, while begins can sound slightly more formal.