La pulbazaro havas uzitajn antikvaĵojn.

Because Esperanto very often forms compound words by joining roots together.

• pulo = flea
• bazaro = bazaar, market

So pulbazaro literally means flea-market. This is a normal Esperanto-style compound, not an unusual spelling choice.

Because uzitajn antikvaĵojn is one noun phrase: used antiques.

The word uzitajn is just an adjective describing antikvaĵojn, so Esperanto only needs one definite article:

• la pulbazaro = the flea market

There is no need to repeat la before the adjective or the object noun.

Also, la never changes form in Esperanto. It stays la no matter the number or grammatical role.

Havas is from havi, meaning to have.

So:

• La pulbazaro havas... = The flea market has...

This can mean literal possession, but in a shop or market context it often means something like:

• has in stock
• carries
• offers
• has for sale

If you used estas, the meaning would be very different. Estas means is/are, not has.

Because it is:

• a noun: -o
• plural: -j
• a direct object: -n

So the ending breaks down like this:

• antikvaĵo = an antique item
• antikvaĵoj = antique items
• antikvaĵojn = antique items, as the direct object

In this sentence, the flea market is the subject, and the antiques are the thing it has, so antikvaĵojn takes the accusative -n.

Because adjectives in Esperanto agree with the nouns they describe.

Since antikvaĵojn is:

• plural
• accusative

the adjective must match it:

• uzita = used
• uzitaj = used, plural
• uzitajn = used, plural accusative

So:

• uzitajn antikvaĵojn

is correct because both words match in number and case.

Uzita comes from the verb uzi, meaning to use.

It is the past passive participle used as an adjective:

• uzi = to use
• uzita = used

In a sales context, uzita often means second-hand or previously used.

So uzitajn antikvaĵojn means used antiques or second-hand antiques.

It is made from:

• antikva = antique, ancient, old
• -aĵ- = a thing characterized by that quality

So:

• antikvaĵo = an antique object, an antique item

The suffix -aĵ- is very useful in Esperanto. It often turns an adjective or verb idea into a concrete thing.

Here it helps create the sense of an antique piece/object, not just the quality antique.

It can feel slightly redundant from an English-speaking point of view, yes, because antiques are often assumed to be old and previously owned.

But grammatically, the phrase is perfectly fine.

Using uzitajn can still add a nuance such as:

• emphasizing that the items are second-hand
• contrasting them with new antique-style items
• simply describing the stock in a straightforward way

So even if the wording feels a bit repetitive semantically, it is not wrong.

Yes, Esperanto allows more flexibility than English because the accusative -n shows what the direct object is.

For example, these are understandable:

• La pulbazaro havas uzitajn antikvaĵojn.
• Uzitajn antikvaĵojn havas la pulbazaro.

However, the first version is the most neutral and natural for beginners:

• subject + verb + object

So the original sentence is the best standard order to learn first.