Sunt cinci chiriași aici.

Romanian often uses the verb a fi (to be) for existence, where English uses there is / there are.

So Sunt cinci chiriași aici is literally something like Are five tenants here, but naturally it means There are five tenants here.

English needs the dummy subject there. Romanian does not.

Because cinci chiriași is plural, and the verb agrees with that plural idea.

• Este un chiriaș aici = one tenant
• Sunt cinci chiriași aici = five tenants

So a learner can think:

• singular quantity -> este / e
• plural quantity -> sunt

Yes. Sunt can mean both:

• I am
• they are

Romanian often relies on context.

For example:

• Sunt obosit. = I am tired.
• Sunt cinci chiriași aici. = There are / they are five tenants here in an existential sense

In your sentence, it clearly is not I am, because cinci chiriași follows it.

The singular is chiriaș.

So:

• un chiriaș = one tenant
• doi / trei / cinci chiriași = two / three / five tenants

Chiriaș is a masculine noun. Its plural is chiriași.

After numbers, Romanian normally uses the noun without the definite article.

So you say:

• cinci chiriași
• not cinci chiriașii

This is similar to English, where you say five tenants, not five the tenants.

If you want to make them definite and specific, Romanian usually does it in another way, for example:

• cei cinci chiriași = the five tenants

No. Cinci is invariable.

That means it stays cinci regardless of the gender of the noun:

• cinci chiriași
• cinci case
• cinci fete

Unlike one or two, which can show gender in Romanian in some contexts, cinci does not change.

Yes. Romanian word order is fairly flexible.

These are all possible:

• Sunt cinci chiriași aici.
• Aici sunt cinci chiriași.
• Sunt aici cinci chiriași.

They all mean basically the same thing, but the emphasis changes a little:

• Sunt cinci chiriași aici. = neutral
• Aici sunt cinci chiriași. = emphasizes here
• Sunt aici cinci chiriași. = also highlights location, but may sound a bit more shaped by context

The version you were given is a very natural neutral sentence.

Yes, that is grammatical, but it is not always the most natural everyday choice.

• Sunt cinci chiriași aici sounds very normal and conversational.
• Există cinci chiriași aici sounds more formal, more abstract, or more like you are emphasizing existence itself.

In ordinary speech, Romanian often prefers sunt in this kind of sentence.

If the group is all female, Romanian would normally use the feminine form:

• singular: chiriașă
• plural: chiriașe

So:

• Sunt cinci chiriașe aici. = if all five are women

If the group is mixed, or if the gender is unknown, Romanian usually uses the masculine plural:

• Sunt cinci chiriași aici.

A rough guide:

• cinci -> roughly cheench, with both c sounds like ch
• chiriași -> roughly kee-ree-AHSH, with ș like sh in ship
• aici -> roughly ah-EECH

A few useful details:

• ș = sh
• ch before i or e is pronounced like k, not like English ch
• the final written -i in words like chiriași and aici is very short and often just slightly softens the preceding consonant

No separate subject is needed.

In English, there are includes there, but that there is not really a normal subject with meaning. It is just part of the structure.

Romanian does not need that. The sentence can simply begin with the verb:

• Sunt cinci chiriași aici.

So there is no hidden they here. It is just an existential sentence: there are five tenants here.