Acesta este sfârșitul.

Acesta is the standalone demonstrative pronoun meaning this one / this.

• acesta = this one
• acest = this
  • a noun after it

So you can say:

• Acesta este sfârșitul. = This is the end.
• Acest sfârșit... = This end...

In your sentence, this stands by itself, so acesta is the correct form.

Este is the 3rd person singular present of a fi (to be).

So it means is.

• eu sunt = I am
• tu ești = you are
• el/ea este = he/she is

In everyday Romanian, este is very often shortened to e:

• Acesta este sfârșitul.
• Acesta e sfârșitul.

Both are correct. Este sounds slightly more full or careful; e is very common in speech.

The ending -ul is the definite article attached to the noun.

Romanian usually puts the at the end of the noun, not before it.

• sfârșit = end
• sfârșitul = the end

This is one of the big differences from English. Instead of a separate word like the, Romanian often adds an ending to the noun itself.

Because the sentence refers to a specific end: the end, not just an end or end in general.

Compare:

• Este sfârșit. = It is finished / It is over.
• Este sfârșitul. = It is the end.

So in Acesta este sfârșitul, the speaker is identifying something as the end, which is why the definite form is used.

Yes. Acesta is masculine singular.

Some related forms are:

• acesta = this one (masculine singular)
• aceasta = this one (feminine singular)
• aceștia = these ones (masculine plural)
• acestea = these ones (feminine/neuter plural)

So the form changes depending on gender and number.

Here, acesta matches sfârșitul, which is a masculine singular noun.

Yes, very often.

• Acesta este sfârșitul. = more formal, more careful, more literary
• Asta e sfârșitul. = more natural in everyday speech

A native speaker would commonly say Asta e sfârșitul in conversation.
Acesta este sfârșitul is still perfectly correct, but it sounds a bit more formal or emphatic.

The normal, neutral order is:

Acesta este sfârșitul.

Romanian word order is fairly flexible, but changing it usually changes the emphasis.

For example:

• Acesta este sfârșitul. = neutral
• Sfârșitul este acesta. = more marked, emphasizing this is the end
• Acesta sfârșitul este = not normal Romanian

So the sentence you have is the standard order.

Not in this sentence, if you want the meaning this is the end.

Romanian often drops personal subject pronouns because the verb already shows the person:

• Sunt aici. = I am here.
• Este târziu. = It is late.

But acesta is not just an optional subject pronoun like he or she. It is a demonstrative meaning this. If you remove it, you change the sentence:

• Acesta este sfârșitul. = This is the end.
• Este sfârșitul. = It is the end / This is the end only from context

So if you specifically want this, you should keep acesta.

A rough pronunciation is:

sfârșitul ≈ sfur-shi-tul

Two letters may look unfamiliar:

• ș = sh, like in shoe
• â = a central vowel that English does not really have; it is similar to the Romanian î

So:

• sfâr sounds roughly like sfur
• și sounds like shee
• tul sounds like tool with a shorter vowel

Also, the stress is usually on the second syllable:

sfâr-ȘI-tul

Yes, but it is not exactly the same in tone.

• sfârșitul is the usual word for the end
• finalul can also mean the end, but often sounds more like the finale, the last part, or the final

So:

• Acesta este sfârșitul. sounds like the standard way to say This is the end.
• Acesta este finalul. can work, but it may sound slightly different in nuance depending on context.

If you are learning the most direct, standard version of the sentence, sfârșitul is the best choice.