Surprovu la lozan jakon.

Yes. Surprovu is a single Esperanto verb form.

• Base verb: provi = to try, to test
• With the prefix sur-: surprovi = to try on (especially clothes)

So Esperanto uses one verb where English often uses a verb + particle, like try on.

Because -u is the Esperanto verb ending for a command, request, or exhortation.

So:

• surprovi = to try on
• surprovas = tries on / is trying on
• surprovis = tried on
• surprovos = will try on
• surprovu = try on!

In this sentence, Surprovu la lozan jakon is a command or suggestion: Try on the loose jacket.

In Esperanto, commands often leave the subject unstated, just like English often does.

• Surprovu la lozan jakon. = Try on the loose jacket.

The understood subject is you, but it does not need to be said.

If you wanted to include it for emphasis, you could say:

• Vi surprovu la lozan jakon.

But normally that sounds more emphatic than necessary.

Because jakon is the direct object, and in Esperanto direct objects take -n. Adjectives must agree with the nouns they describe, so lozan also gets -n.

Breakdown:

• jako = jacket
• jakon = jacket as a direct object
• loza = loose
• lozan = loose, matching an -n noun

So:

• la loza jako = the loose jacket
• la lozan jakon = the loose jacket, as the thing being tried on

This agreement is a very important Esperanto rule.

Here loza means loose, not tight, or roomy.

In clothing contexts, it usually means the garment is not close-fitting.

So la lozan jakon means the loose jacket or the roomy jacket.

Esperanto has only one article: la, which means the.

There is no separate word for a or an.

So:

• jako = a jacket / jacket
• la jako = the jacket

That means:

• Surprovu lozan jakon. could mean Try on a loose jacket.
• Surprovu la lozan jakon. means Try on the loose jacket.

Yes, you could, but it is a little less specific.

• provi = to try, test
• surprovi = to try on

So:

• Provu la lozan jakon. can still be understood, especially from context.
• Surprovu la lozan jakon. clearly means put it on to see how it fits.

With clothing, surprovi is the more precise choice.

Yes. Esperanto word order is fairly flexible because the -n ending marks the direct object.

The most neutral version is:

• Surprovu la lozan jakon.

But you could also say:

• La lozan jakon surprovu.

That changes the emphasis, but the meaning stays basically the same because jakon is still marked as the object.

For learners, though, the standard verb-first order in commands is the safest choice.

Because the noun is singular.

• jako = jacket
• jakoj = jackets

In the sentence, we have jakon, not jakojn.

So:

• jakon = one jacket as a direct object
• jakojn = more than one jacket as direct objects

The adjective would also change:

• la lozan jakon = the loose jacket
• la lozajn jakojn = the loose jackets

A simple pronunciation guide is:

soor-PRO-voo la LO-zan YAH-kon

A few useful points:

• j in Esperanto sounds like English y
• z sounds like the z in zoo
• stress usually falls on the second-to-last syllable:
  • surPROvu
  • LOzan
  • JAkon

So jako sounds like YAH-ko, not like English jacket with an English j sound.