La konekto ne estas rapida hodiaŭ.

In Esperanto, -o marks a noun. So konekto is a noun meaning connection.

This is one of the most basic Esperanto endings:

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

So in this sentence:

• konekto = connection
• rapida = fast
• estas = is

La is the definite article, meaning the.

So:

• la konekto = the connection
• konekto = a connection or connection in a more general sense

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

In Esperanto, ne usually goes directly before the word it negates.

Here it negates the verb:

• ne estas = is not

So:

• La konekto estas rapida. = The connection is fast.
• La konekto ne estas rapida. = The connection is not fast.

That placement is very normal and natural.

Estas is the present tense of esti (to be). It is used because the sentence describes a state or quality of the connection: it is fast or is not fast.

So this is a linking structure:

• subject: La konekto
• verb: estas
• adjective: rapida

This is just like English:

• The connection is fast
• The connection is not fast

Because rapida describes the noun konekto.

In Esperanto:

• -a adjectives describe nouns
• -e adverbs describe verbs, adjectives, or whole clauses

Here, rapida means fast as a property of the connection.

Compare:

• La konekto estas rapida. = The connection is fast.
• La konekto funkcias rapide. = The connection works quickly.

So rapida is correct because it describes konekto, not the action.

Yes. In Esperanto, adjectives agree with the nouns they describe.

Since konekto is:

• singular
• not accusative

the adjective is also:

• singular
• not accusative

So we get:

• konekto rapida

With the article:

• la konekto ... rapida

If the noun were plural, the adjective would also be plural:

• La konektoj estas rapidaj. = The connections are fast.

If accusative were needed, the adjective would also take -n:

• Mi vidas la rapidan konekton. = I see the fast connection.

Because there is no direct object here.

The sentence uses esti (to be), which links the subject to a description. With esti, the adjective after it does not take -n.

So:

• La konekto = the subject
• estas rapida = describes the subject
• hodiaŭ = tells us when

No direct object is present, so no accusative -n is needed.

Hodiaŭ means today, and here it functions as a time adverb.

It tells when the statement is true:

• La konekto ne estas rapida hodiaŭ. = The connection is not fast today.

Many time words in Esperanto can be used adverbially without needing a special ending in practice, and hodiaŭ is a very common example.

Yes. Esperanto word order is fairly flexible, as long as the meaning stays clear.

These are all possible:

• La konekto ne estas rapida hodiaŭ.
• Hodiaŭ la konekto ne estas rapida.
• La konekto hodiaŭ ne estas rapida.

They all mean roughly the same thing, though the emphasis may shift slightly. Putting hodiaŭ first can emphasize today.

Usually, no—not in standard usage.

Rapida is an adjective meaning fast, while rapidas would treat rapid- as a verb, to be fast / to move quickly, which is not the normal way to talk about a connection in this sentence.

The standard and clearest version is:

• La konekto ne estas rapida hodiaŭ.

Esperanto often uses esti + adjective just as English does.

Yes, konekto is a normal and understandable word for connection, including an internet connection.

Depending on context, Esperanto speakers might also say things like:

• retkonekto = internet connection
• interreta konekto = internet connection

But la konekto is completely fine if the context already makes it clear what kind of connection you mean.

You only need to change the form of esti:

• La konekto ne estis rapida hodiaŭ. = The connection was not fast today.
• La konekto ne estos rapida hodiaŭ. = The connection will not be fast today.

Esperanto verb endings are regular:

• -as = present
• -is = past
• -os = future

So:

• estas = is
• estis = was
• estos = will be

The structure is:

• La konekto = subject
• ne estas = negative form of is
• rapida = predicate adjective
• hodiaŭ = time expression

So the pattern is:

subject + ne + esti + adjective + time word

This is a very common and useful Esperanto sentence pattern.