Parcul este sigur.

Because Romanian usually puts the definite article at the end of the noun, not as a separate word before it.

• parc = park / a park
• parcul = the park

So -ul is the masculine/neuter singular definite article here.

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

So the structure is:

• Parcul = the park
• este = is
• sigur = safe

Unlike in some languages, in standard Romanian you normally keep the verb to be in this kind of sentence.

Yes. E is a very common short form of este in everyday speech.

• Parcul este sigur. = more neutral/full
• Parcul e sigur. = very natural in conversation

Both are correct.

It actually already has the correct form for parcul.

Parcul is masculine singular, so the adjective also appears in the masculine singular form:

• masculine singular: sigur
• feminine singular: sigură
• masculine plural: siguri
• feminine/neuter plural: sigure

Examples:

• Parcul este sigur.
• Zona este sigură.
• Băieții sunt siguri.
• Străzile sunt sigure.

Because Romanian usually expresses the by attaching it to the noun itself.

So instead of something like English the park, Romanian says:

• parcul

This is one of the most important differences between English and Romanian.

A simple learner-friendly pronunciation guide would be:

PAR-kool YES-te see-GOOR

A few notes:

• parcul: the u is pronounced, so it is not like English parkl
• este: often sounds like YES-te
• sigur: the g is a hard g, like in go

Parcul este sigur is the normal, neutral word order.

Romanian word order is somewhat flexible, but this is the most straightforward version for a basic statement:

• subject
  • verb
    • adjective

Other orders may appear for emphasis, but a learner should start with Parcul este sigur.

Yes. Sigur can also mean sure or certain, depending on context.

For example:

• Sunt sigur. = I am sure.
• Un loc sigur. = a safe place

In Parcul este sigur, the meaning is clearly safe.

Both can be used, but they are slightly different in feel.

• Parcul este sigur. = The park is safe.
• Parcul este în siguranță. usually sounds more like The park is secure / in safety, which is less natural in this context

For describing whether a place is safe, sigur is the normal and natural choice.

You would say:

Un parc este sigur.

Compare:

• Un parc = a park
• Parcul = the park

So the difference is:

• Un parc este sigur. = A park is safe.
• Parcul este sigur. = The park is safe.

Parc is a neuter noun in Romanian.

That means:

• in the singular, it behaves like a masculine noun
• in the plural, it behaves like a feminine noun

So in the singular you get:

• un parc
• parcul
• sigur

And in the plural:

• două parcuri
• parcurile
• sigure

This is why sigur is used in the sentence: neuter singular nouns take the same adjective form as masculine singular nouns.

Not always. In everyday speech, many speakers prefer the shorter e:

• Parcul e sigur.

But este is still completely correct and common, especially in careful speech, writing, or when speaking more formally.