Mi elektos abonon, kondiĉe ke la bendlarĝo estos granda.

Because -os is the Esperanto future-tense ending.

• elektas = chooses / is choosing
• elektis = chose
• elektos = will choose

So Mi elektos abonon means I will choose a subscription.

The -n marks the direct object.

In this sentence, abonon is the thing being chosen, so it takes the accusative ending:

• Mi elektos abonon = I will choose a subscription

Compare:

• abono = a subscription
• abonon = a subscription as the direct object of the verb

This is very common in Esperanto: the noun directly affected by the action usually gets -n.

kondiĉe ke means provided that, on condition that, or as long as in a conditional sense.

It is a set expression:

• kondiĉe = conditionally / on condition
• ke = that

Together they introduce a condition:

• Mi elektos abonon, kondiĉe ke... = I will choose a subscription, provided that...

So even though it has two words, you should learn it as one useful phrase.

Yes, but the meaning changes slightly.

• se = if
• kondiĉe ke = provided that / on condition that

So:

• Mi elektos abonon, se la bendlarĝo estos granda = I will choose a subscription if the bandwidth is large
• Mi elektos abonon, kondiĉe ke la bendlarĝo estos granda = I will choose a subscription provided that the bandwidth is large

kondiĉe ke sounds a bit stronger and more formal. It suggests that this is a specific requirement.

Because this sentence describes a real future possibility, not an unreal or hypothetical situation.

• estos = will be
• estus = would be

In Esperanto, when you mean a genuine future condition, -os is normal:

• Mi elektos abonon, kondiĉe ke la bendlarĝo estos granda.

That means the speaker expects this condition might really be met.

If you used estus, it would sound more hypothetical or contrary-to-fact, more like English would be in a less direct or less real situation.

Because granda is not a direct object here. It is a predicate adjective after esti.

In la bendlarĝo estos granda:

• la bendlarĝo = the subject
• estos = will be
• granda = big / large

After esti, adjectives describe the subject and normally do not take -n.

Compare:

• Mi vidas grandan domon = I see a big house
  
  • grandan takes -n because it describes the direct object domon
• La domo estas granda = The house is big
  
  • granda has no -n because it is a predicate adjective

Esperanto uses la much like English the.

• la bendlarĝo = the bandwidth
• abonon = a subscription / some subscription

Here, la bendlarĝo refers to a specific bandwidth that both speaker and listener can identify, such as the bandwidth of a particular service being discussed.

But abonon is indefinite: the speaker is saying they will choose a subscription, not necessarily a specifically identified one.

Esperanto has no separate word for a/an, so the bare noun often covers that meaning.

Yes. Esperanto often creates vocabulary by combining roots into one word.

The general idea of compounds is:

• the final part is the main idea
• the earlier part modifies it

So in bendlarĝo:

• larĝo = width
• bend- specifies what kind of width

That gives the sense of bandwidth.

This kind of word-building is very typical in Esperanto and is one of the language’s most useful features.

Yes. Because Esperanto marks grammar clearly with endings, word order is fairly flexible.

You could also say:

• Kondiĉe ke la bendlarĝo estos granda, mi elektos abonon.

This means the same thing. The difference is mostly style and emphasis:

• starting with Mi elektos abonon emphasizes the choice
• starting with Kondiĉe ke... emphasizes the condition first

Both are correct.

The comma separates the main clause from the subordinate clause.

• Main clause: Mi elektos abonon
• Subordinate clause: kondiĉe ke la bendlarĝo estos granda

This is similar to English punctuation before clauses such as if, provided that, or because. In Esperanto, commas are commonly used to make clause boundaries clear, especially with ke-clauses.