Ŝi surprovis la veston, kaj ĝi konvenis.

Because la veston is the direct object of surprovis.

• Ŝi = the subject, the person doing the action
• la veston = the thing she tried on

In Esperanto, direct objects usually take -n.

So:

• vesto = a garment
• veston = a garment as the direct object

Surprovis is the past tense of surprovi, which means to try on.

It is built from:

• provi = to try, test
• sur- = a prefix meaning on or onto

So surprovi is more specific than just provi. It means putting something on to see how it fits or looks.

Yes, many people would understand Ŝi provis la veston in context, especially if it is obviously about clothing.

But surprovi is more precise, because it clearly means try on rather than just try in a general sense.

So:

• provi = try, test
• surprovi = try on

Not necessarily. Vesto usually means garment or item of clothing in a general sense.

If the translation you saw says dress, that is probably a context-based translation, not the most literal one.

If you specifically want dress as a woman’s dress, robo is more exact.

So:

• vesto = garment, clothing item
• robo = dress

Because ĝi refers to the garment, not to the woman.

• ŝi = she
• ĝi = it

In kaj ĝi konvenis, the subject is the clothing item: it fit or it suited.

If you used ŝi, then the sentence would be talking about her as the subject of konvenis, which is not the intended meaning here.

Konvenis is the past tense of konveni.

In this kind of sentence, it can mean things like:

• fit
• suited
• was suitable
• looked right

With clothing, konveni often suggests more than just size. It can mean the garment was right for her in appearance or suitability, and sometimes also that it fit well.

So the idea is not just physical measurement, but also that the clothing worked well for her.

It is often understood from context.

A fuller version could be:

Ŝi surprovis la veston, kaj ĝi konvenis al ŝi.

That means She tried on the garment, and it suited/fitted her.

In the original sentence, al ŝi is omitted because it is obvious who the garment is being judged in relation to.

So Esperanto can leave out information that is already clear from context.

Because -is is the Esperanto past tense.

• surprovis = tried on
• konvenis = fit / suited

Both actions are being described as past events.

Esperanto uses the same past-tense ending very regularly, so once you know -is, you can recognize past tense immediately.

Because here ĝi is the subject of konvenis, not the object.

Compare:

• Ŝi surprovis la veston = la veston is the object, so it has -n
• ĝi konvenis = ĝi is the subject, so there is no -n

If it were an object, you would use ĝin.

For example:

• Ŝi surprovis ĝin = She tried it on

A rough guide is:

• ŝi ≈ shee
• ĝi ≈ jee

A few helpful points:

• ŝ sounds like sh
• ĝ sounds like the j in judge
• Esperanto stress is usually on the second-to-last syllable

So:

• surprovis → sur-PRO-vis
• veston → VES-ton
• konvenis → kon-VE-nis

A rough pronunciation of the whole sentence is:

shee soor-PRO-vees la VES-ton, kai jee kon-VE-nees