Acesta este momentul.

Because acesta is a demonstrative pronoun: it means this one / this and can stand by itself.

• acesta = this (one)
• acest = this before a noun

So:

• Acesta este momentul. = This is the moment.
• Acest moment... = This moment...

A very common learner mistake is using acest by itself. In standard Romanian, if no noun follows, you normally use acesta.

Momentul is moment + the definite article.

• moment = moment
• momentul = the moment

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

So -ul here is the masculine singular definite article.

Because Romanian has a postposed definite article. That means the article is attached to the noun.

Compare:

• moment = a moment / moment
• momentul = the moment

This is one of the biggest differences from English. Instead of the moment, Romanian says one word: momentul.

It may look that way at first, but the structure is normal.

The sentence is built like this:

• Acesta = this
• este = is
• momentul = the moment

So the logic is:

This is the moment.

English also has two definite-looking elements here: this and the moment. Romanian is doing the same thing, just with its own grammar.

Yes. Este and e both mean is.

• Acesta este momentul. = full form, neutral/standard
• Acesta e momentul. = shorter, very common in speech

Both are correct.
In everyday conversation, e is extremely common.

Yes. Ăsta is a more colloquial spoken form of acesta.

So:

• Acesta este momentul. = more careful, neutral, a bit more formal
• Ăsta e momentul. = more conversational and natural in speech

Both are correct; the difference is mainly register.

A rough English-friendly pronunciation is:

ah-CHES-tah YES-teh moh-MEN-tool

A few helpful notes:

• ce in acesta sounds like che in check
• word-initial e in este sounds like ye
• u in -tul is like oo
• stress is usually:
  • aCESta
  • ESte
  • moMENtul

A more technical pronunciation is approximately:

/aˈt͡ʃes.ta ˈjes.te moˈmen.tul/

Because that would be a different structure.

• Acesta este momentul. = This is the moment.
• Acest moment este important. = This moment is important.

In the first sentence, this stands alone, so Romanian uses acesta.
In the second, this directly modifies moment, so Romanian uses acest.

Yes. Acesta is masculine singular.

That matches moment, which is a masculine noun in Romanian.

Related forms include:

• acesta = masculine singular
• aceasta = feminine singular
• aceștia = masculine plural
• acestea = feminine plural

So if the thing referred to were feminine, you would use aceasta, not acesta.

The normal, neutral order here is:

Acesta este momentul.

That is the most straightforward way to say it.

Romanian does allow some flexibility in word order, but changing it can change the emphasis or even the structure. For example:

• momentul acesta usually means this moment
• Acesta e momentul still means This is the moment

So for this exact idea, Acesta este momentul is the safest standard pattern.

It can do any of those, depending on context. In this sentence, it points to the present decisive moment / the right moment / the moment being discussed.

Romanian acesta works much like English this: it identifies something as near, immediate, or just mentioned. In a sentence like this, it often has an emphatic feeling, like:

• This is it.
• This is the moment.

So the grammar is simple, but the sentence can sound dramatic or emphatic depending on context.