Omul este aici.

Because -ul is the Romanian definite article, attached to the end of the noun.

• om = man / person
• omul = the man / the person

Unlike English, Romanian usually puts the at the end of the noun instead of before it.

om is a masculine noun.

In the singular:

• indefinite: un om = a man / a person
• definite: omul = the man / the person

So -ul here is the masculine/neuter singular definite ending used in this form.

Este means is and is the 3rd person singular form of a fi = to be.

So:

• Omul este aici. = The man is here.

In everyday Romanian, people very often use the shorter form e:

• Omul e aici.

Both are correct. Este sounds a bit more formal or careful; e is very common in speech.

Normally, no. In a sentence like this, Romanian usually keeps the verb.

So you say:

• Omul este aici.
• Omul e aici.

Not normally just:

• Omul aici.

Romanian generally needs the equivalent of is in this kind of present-tense sentence.

Yes, aici means here.

It refers to location near the speaker, just like English here:

• Sunt aici. = I am here.
• Cartea este aici. = The book is here.

A common contrast is:

• aici = here
• acolo = there

This is the most neutral word order:

• Omul = subject
• este = verb
• aici = location

But Romanian can change word order for emphasis more easily than English. For example:

• Aici este omul. = The man is here / Here is the man.

This can sound more emphatic or context-dependent. For a basic learner sentence, Omul este aici is the safest standard order.

A simple learner-friendly pronunciation guide:

• Omul ≈ OH-mool
• este ≈ YES-te
• aici ≈ ah-EECH

So the whole sentence is roughly:

• OH-mool YES-te ah-EECH

A few notes:

• Romanian e at the start of este sounds like ye to English ears.
• ci in aici sounds like ch.
• Stress is commonly heard as Omul ESTE aICI, though natural rhythm can vary.

It can mean either, depending on context.

• In some contexts, om means man.
• In many contexts, it more generally means person / human being.

So Omul este aici could mean:

• The man is here or
• The person is here

The correct choice depends on the situation, even if English may prefer one translation.

The indefinite version is:

• Un om este aici. = A man / A person is here.

Compare:

• om = man / person
• un om = a man / a person
• omul = the man / the person

This is a very useful pattern in Romanian:

• un = a
• noun + definite ending = the

Yes, but it means something slightly different.

• omul = the man or the person
• bărbatul = the man in the sense of an adult male

So if you specifically mean an adult male, Bărbatul este aici works well.
If you want a more general word that can also mean person, Omul este aici is broader.