La ŝtopilo konektas la kablon al la modemo.

The -n marks the direct object in Esperanto.

In this sentence:

• La ŝtopilo = the plug → the thing doing the action
• konektas = connects
• la kablon = the cable → the thing being connected

So kablon has -n because it is the object of the verb konektas.

Because la modemo comes after the preposition al.

In Esperanto, a noun after a preposition usually does not take -n just because it is part of the sentence. Here:

• al la modemo = to the modem

The -n is already used on kablon to show that the cable is the direct object.
The modem is introduced by al, so modemo stays without -n.

Al usually means to.

In this sentence, it shows the thing that the cable is being connected to:

• konektas la kablon al la modemo = connects the cable to the modem

So al marks the target or destination of the connection.

-as is the Esperanto present-tense verb ending.

So:

• konekti = to connect
• konektas = connects / is connecting

Esperanto verbs always use fixed endings, so -as always means present tense.

Because la means the, and Esperanto uses it before each noun when the noun is definite.

So:

• La ŝtopilo = the plug
• la kablon = the cable
• la modemo = the modem

Unlike English, Esperanto does not have an indefinite article like a/an. It only has la for the.

In Esperanto:

• -o marks a noun
• -n marks the accusative (usually the direct object)

So:

• ŝtopilo = a noun, plug
• modemo = a noun, modem
• kablon = noun + object marker, cable as the direct object

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

Yes, Esperanto word order is fairly flexible because the -n ending helps show what is the object.

The normal order here is:

• La ŝtopilo konektas la kablon al la modemo.

But other orders can still be understood, especially in poetry or for emphasis, because kablon is clearly marked as the object.

Still, for learners, it is best to use the standard subject–verb–object order unless you have a reason to change it.

The letter ŝ is pronounced like English sh.

So ŝtopilo begins roughly like shto-.

A simple approximation is:

• ŝto-PI-lo

with ŝ = sh

Also remember that Esperanto spelling is very regular: each letter has one main sound.

Yes. Ŝtopilo commonly means plug, especially an electrical plug.

So in this sentence, La ŝtopilo is the plug that connects the cable to the modem.

A learner may also later meet related words, but ŝtopilo is a normal and useful word for plug.

Because al fits the idea of connecting something to something else.

• al = to
• kun = with

In English, we sometimes say connect X to Y or connect X with Y, but in this sentence Esperanto uses al to show the endpoint:

• konekti la kablon al la modemo = connect the cable to the modem

That is a very natural choice in Esperanto.

Here are the dictionary forms:

• la = the
• ŝtopilo = plug
• konekti = to connect
• kablo = cable
• al = to
• modemo = modem

In the sentence, only two words are changed from their basic dictionary form:

• konekti → konektas because the verb is in the present tense
• kablo → kablon because it is the direct object

Yes. Esperanto -as covers the general present tense, so depending on context it can correspond to English:

• connects
• is connecting

Most often, the simplest translation is The plug connects the cable to the modem, but context decides the exact English style.