La artiko restas movebla kaj fleksebla.

In Esperanto, -o marks a noun. So artiko is a noun meaning joint.

This is one of the most important regular patterns in Esperanto:

• -o = noun
• -a = adjective
• -e = adverb
• -i = infinitive verb

So in this sentence:

• artiko = a joint
• movebla = movable
• fleksebla = flexible

La is the Esperanto definite article, meaning the.

So:

• artiko = a joint or joint in a general sense
• la artiko = the joint

Esperanto has only one article, la, and it does not change for gender, number, or case.

Restas is the present-tense form of resti, meaning to remain, to stay, or to continue to be.

Esperanto verb endings are very regular:

• -as = present
• -is = past
• -os = future
• -us = conditional
• -u = command/wish
• -i = infinitive

So:

• resti = to remain
• restas = remains / stays

In this sentence, restas links the subject to its qualities: the joint remains movable and flexible.

Because they are adjectives describing artiko.

In Esperanto, adjectives end in -a and agree with the noun they describe in number and case. Here:

• artiko = singular noun
• movebla = singular adjective
• fleksebla = singular adjective

So the adjectives match the noun.

The suffix -ebla means able to be or capable of being.

It is built from:

• a root
• plus -ebl-
• plus the adjective ending -a

So:

• movi = to move
  → movebla = movable, able to be moved

• fleksi = to bend
  → fleksebla = flexible, able to bend

This suffix is very useful in Esperanto. For example:

• legi = to read
  → legebla = readable

• manĝi = to eat
  → manĝebla = edible

They are similar, but not identical.

• movebla = movable
  Something can be moved or can move freely.

• fleksebla = flexible
  Something can bend without breaking.

For a joint, both ideas make sense:

• it can move
• it can bend

So the sentence gives two related qualities of the joint.

The -n ending usually marks the direct object in Esperanto.

But in this sentence, there is no direct object. The structure is:

• La artiko = subject
• restas = verb
• movebla kaj fleksebla = predicate adjectives

Since movebla and fleksebla are describing the subject after restas, they do not take -n.

Compare:

• La artiko restas fleksebla. = The joint remains flexible.
• Mi movas la artikon. = I move the joint.

In the second sentence, artikon gets -n because it is the direct object.

Because everything here is singular.

• artiko = one joint
• movebla = movable, singular
• fleksebla = flexible, singular

If it were plural, you would see -j:

• La artikoj restas moveblaj kaj flekseblaj.
  = The joints remain movable and flexible.

So adjectives also take -j when they describe a plural noun.

Kaj means and. It simply joins the two adjectives:

• movebla
• fleksebla

So movebla kaj fleksebla means movable and flexible.

It is similar to is in that it connects the subject with a description, but it adds the idea of continuing or remaining.

Compare:

• La artiko estas movebla. = The joint is movable.
• La artiko restas movebla. = The joint remains movable.

So restas suggests that this quality continues to be true.

Yes, Esperanto word order is fairly flexible, though the normal order here is very natural:

• La artiko restas movebla kaj fleksebla.

You might also see variations for emphasis, but the standard subject-verb-description order is the clearest for learners.

Because Esperanto uses endings to show grammar, word order is often freer than in English, but that does not mean all orders are equally natural. This sentence is already in a very normal order.

A simple approximate pronunciation is:

la ar-TEE-ko RES-tas mo-VE-bla kai flek-SE-bla

A few useful points:

• ti in artiko is pronounced clearly: ar-TEE-ko
• e is always a clear vowel, like in ten but steadier
• j is pronounced like English y
• so kaj sounds like kai or kahy, not like English jay

Esperanto spelling is very regular, so once you know the sounds, pronunciation is usually straightforward.

Yes. That is exactly the right way to think about it.

The root is mov-. From that root you can build:

• movi = to move
• movo = movement
• moviĝi = to move oneself / to move
• movebla = movable

The e in movebla is part of the suffix pattern -ebla attached to the root. The same thing happens with fleksebla from fleks-.

Esperanto word-building is very systematic, so noticing these parts will help you learn vocabulary much faster.