La segilo restas sub la ŝtupetaro.

La is the Esperanto definite article, meaning the. It does not change for gender, number, or case.

In this sentence, it appears before both nouns because both are definite:

• la segilo = the saw
• la ŝtupetaro = the ladder

Esperanto does not have a separate word for a/an. So a saw would just be segilo.

Because -o is the normal noun ending in Esperanto.

So:

• segilo is a noun
• ŝtupetaro is a noun

This is one of the most basic patterns in the language. If a word ends in -o, it is a noun. For comparison:

• -a = adjective
• -e = adverb
• -i = infinitive verb
• -as = present tense verb

That is why restas is the verb here, while segilo and ŝtupetaro are things.

It is built very regularly:

• seg- = the idea of sawing
• -il- = tool or instrument
• -o = noun

So segilo literally means a tool for sawing.

This is a very common Esperanto pattern. For example:

• tranĉi = to cut
• tranĉilo = a cutting tool, a knife

So learning -il- is very useful.

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

So restas is not just a plain statement of location. It suggests that the saw is still under the ladder, or remains there.

That nuance can matter. Compare:

• La segilo estas sub la ŝtupetaro. = The saw is under the ladder.
• La segilo restas sub la ŝtupetaro. = The saw remains/stays under the ladder.

In Esperanto, -as marks the present tense.

So:

• resti = to remain
• restas = remains / stays

Other common verb endings are:

• -is = past
• -os = future
• -us = conditional
• -u = command or volitive

This system is completely regular, so once you learn the endings, verbs become much easier.

Because sub la ŝtupetaro describes a location, not movement toward a place.

In Esperanto, the accusative -n is often used after a preposition to show direction. But if you are just saying where something is, you usually do not add -n.

So here:

• sub la ŝtupetaro = under the ladder

The saw is already there, so no accusative is needed.

Yes. With -n, it would usually indicate movement to a position under the ladder.

So the contrast is:

• sub la ŝtupetaro = under the ladder, already there
• sub la ŝtupetaron = to under the ladder, moving there

For example:

• La kato kuras sub la ŝtupetaron. = The cat runs to a place under the ladder.

In your sentence, restas describes a state, not movement, so sub la ŝtupetaro is the natural form.

Yes, although it is also perfectly fine to learn it simply as the word for ladder.

It is related to ŝtupo, meaning step. The word can be analyzed as something like a set of little steps:

• ŝtup- = step
• -et- = smallness or lesser degree
• -ar- = a collection or group
• -o = noun

So historically it is very transparent. But in normal use, ŝtupetaro is just the standard word you learn for ladder.

Ŝ is pronounced like sh in ship.

A few useful pronunciation points from this sentence:

• ŝ = sh
• u sounds like oo
• g is always a hard g, as in go
• the stress in Esperanto always falls on the next-to-last syllable

So:

• segilo → se-GI-lo
• restas → RES-tas
• ŝtupetaro → ŝtu-pe-TA-ro

A rough English-style approximation of the full sentence is:

la seh-GEE-loh RES-tahs soob la shtoo-peh-TAH-roh

This sentence uses the most neutral and common order:

subject + verb + prepositional phrase

• La segilo = subject
• restas = verb
• sub la ŝtupetaro = location phrase

Esperanto word order is fairly flexible, so you could move things around for emphasis, such as:

Sub la ŝtupetaro restas la segilo.

That would put more focus on the location. But the original version is the most straightforward and natural in an ordinary context.

You could form a grammatical sentence that way, but the meaning would change.

Without la, the nouns sound less specific:

• segilo = a saw / saws in a general sense
• ŝtupetaro = a ladder / ladder in a general sense

If the intended meaning is specifically the saw and the ladder, then la is the right choice for both nouns.