Ĉi tiu vazo estas malpli peza ol tiu, sed ĝi pli bele montras la florojn.

Ĉi tiu means this.

Esperanto often builds demonstratives in two parts:

• tiu = that
• ĉi = a particle that adds the idea of here / near the speaker

So:

• ĉi tiu = this
• tiu = that

You may also see the order reversed:

• ĉi tiu vazo
• tiu ĉi vazo

Both mean this vase. The version in your sentence, ĉi tiu vazo, is very common.

Vazo is simply the Esperanto noun for vase.

A very basic Esperanto rule is that nouns end in -o. So:

• vazo = vase
• floro = flower
• domo = house

That -o ending tells you immediately that the word is a noun.

Because peza is an adjective, meaning heavy, while pezo would be the noun weight.

Esperanto endings are very regular:

• -o = noun
• -a = adjective
• -e = adverb

So:

• pezo = weight
• peza = heavy
• bele = beautifully

In malpli peza, the speaker is describing the vase, so an adjective is needed: peza.

Malpli peza ol tiu means less heavy than that one.

The pattern is:

• pli ... ol ... = more ... than ...
• malpli ... ol ... = less ... than ...

So:

• pli granda ol = bigger than
• malpli granda ol = less big / smaller than
• malpli peza ol tiu = less heavy than that one

A useful point: malpli is not just mal- added to pli in a fully predictable way in English style; you should learn pli = more and malpli = less as comparison words.

Because Esperanto can use tiu by itself to mean that one when the noun is understood from context.

So in this sentence:

• Ĉi tiu vazo estas malpli peza ol tiu

literally means:

• This vase is less heavy than that one

Since vazo has already been mentioned, repeating it is unnecessary.

Sed means but.

It connects two contrasting ideas:

• This vase is less heavy than that one, but...
• ...it shows the flowers more beautifully.

So sed works very much like English but.

Ĝi refers to ĉi tiu vazo — the first vase.

So the sentence says:

• This vase is less heavy than that one, but it shows the flowers more beautifully.

In Esperanto, ĝi is the usual pronoun for a thing or an animal when you are not using li or ŝi. For objects like a vase, ĝi is exactly what you would expect.

Because bele is an adverb, and here it describes how the vase shows the flowers.

Compare:

• bela = beautiful (adjective)
• bele = beautifully (adverb)

In the sentence:

• ĝi pli bele montras la florojn

the idea is it displays the flowers more beautifully, not it is more beautiful.

So:

• bela vazo = a beautiful vase
• bele montri = to show beautifully

That is why bele, with -e, is used.

Montras is the present-tense form of montri, meaning to show or to display.

Esperanto verbs are very regular:

• montri = to show
• montras = shows / is showing
• montris = showed
• montros = will show

In this sentence, montras la florojn means something like:

• shows the flowers
• displays the flowers

For a vase, English often prefers displays or shows off, but Esperanto uses montri very naturally here.

Because florojn is the direct object of montras.

Esperanto marks direct objects with -n. Also, -j marks plural. So:

• floro = flower
• floroj = flowers
• floron = flower (as a direct object)
• florojn = flowers (as a direct object)

Here the vase is doing the action of showing, and the flowers are what is being shown:

• ĝi montras la florojn = it shows the flowers

So florojn needs both:

• -j for plural
• -n for direct object

Because ol introduces the second part of a comparison, like English than, and that phrase is not a direct object here.

So:

• malpli peza ol tiu = less heavy than that one

The word tiu is simply part of the comparison after ol. It is not the object of a verb, so it does not take -n.

Esperanto word order is fairly flexible, but this sentence uses a very natural, standard order.

The basic structure is:

• Ĉi tiu vazo = subject
• estas malpli peza ol tiu = predicate with comparison
• sed ĝi pli bele montras la florojn = second clause

Because Esperanto marks adjectives, adverbs, objects, and verb tense clearly, some rearrangement is possible. But the given version sounds straightforward and normal.

For a learner, this is a good default pattern to imitate.

Yes, in many contexts pli malpeza could also work, and it would mean lighter or more light in weight.

Compare:

• malpli peza = less heavy
• pli malpeza = more light / lighter

These are often very close in meaning.

However, they are not always identical in nuance:

• malpli peza focuses on having less heaviness
• pli malpeza focuses on having more lightness

In everyday use, either can be understandable, but malpli peza is a very clear and direct comparative structure.

Because the sentence is not talking only about physically containing the flowers; it is talking about how the vase presents them visually.

So ĝi pli bele montras la florojn means something like:

• it shows the flowers more beautifully
• it displays the flowers better / more beautifully

This is a natural way in Esperanto to express that one vase sets off the flowers better than another.

So the focus is on appearance, not just function.