Krom tio, ke orkestro ludos, ankaŭ koruso kantos.

It means besides the fact that... or apart from the fact that....

The parts are:

• krom = besides, apart from
• tio = that, that thing
• ke = that, introducing a clause

So Krom tio, ke orkestro ludos... is literally something like Apart from that, that an orchestra will play..., but in natural English it is better understood as Besides the fact that an orchestra will play....

Because krom is a preposition, and prepositions normally take a noun or pronoun as their object.

A whole ke-clause usually does not follow a preposition directly, so Esperanto often inserts a placeholder word like tio:

• krom tio, ke... = besides the fact that...
• pro tio, ke... = because...
• malgraŭ tio, ke... = although...

So tio is doing useful grammatical work here.

It can mean either, depending on context.

Here it clearly means besides / in addition to, because the second half has ankaŭ:

• ankaŭ koruso kantos = a choir will also sing

That makes the sentence additive: one thing will happen, and another thing will happen too.

If the context were different, krom could mean except. So learners have to read it from context.

Because the sentence is emphasizing that the choir is the additional element.

• ankaŭ koruso kantos = a choir too will sing

If you move ankaŭ, the focus can shift slightly:

• koruso ankaŭ kantos = the choir will also sing
• ankaŭ koruso kantos = the choir too will sing

In practice, both can be understandable, but the given version most naturally highlights koruso as the extra participant.

Because -os is the Esperanto future tense ending.

• ludos = will play
• kantos = will sing

Esperanto verb endings are very regular:

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

So both actions are placed in the future.

Esperanto has no indefinite article.

So:

• orkestro can mean an orchestra or sometimes orchestra in a more general sense
• koruso can mean a choir

Esperanto only has a definite article: la.

So:

• orkestro ludos = an orchestra will play
• la orkestro ludos = the orchestra will play

If the speaker means a specific orchestra already known in the context, la would be used.

Because both are subjects, not direct objects.

In this sentence:

• orkestro ludos = the orchestra is the subject of ludos
• koruso kantos = the choir is the subject of kantos

The accusative -n is mainly used for direct objects and some expressions of direction.

So these forms stay:

• orkestro
• koruso

not orkestron or koruson.

The first comma separates tio from the explanatory ke-clause:

• tio, ke orkestro ludos

This kind of comma is common in Esperanto when a pronoun like tio is followed by a clause explaining it.

The second comma marks the end of the opening subordinate part:

• Krom tio, ke orkestro ludos, ...

After that, the main clause begins:

• ankaŭ koruso kantos

So the commas help show the structure of the sentence.

Yes. Ludi can be used without an object when the meaning is simply perform/play music.

So orkestro ludos can naturally mean:

• an orchestra will perform
• an orchestra will play

If you want to mention the thing being played, you can add an object:

• La orkestro ludos simfonion. = The orchestra will play a symphony.

But it is not required.

Yes. The given sentence is grammatical, but many speakers might also say:

• Ne nur orkestro ludos, sed ankaŭ koruso kantos.
  • Not only will an orchestra play, but a choir will also sing.

That version makes the not only X, but also Y structure very explicit.

Still, Krom tio, ke orkestro ludos, ankaŭ koruso kantos is understandable and correctly built.

It has two main parts:

1. Krom tio, ke orkestro ludos

   • an introductory subordinate phrase
   • besides the fact that an orchestra will play

2. ankaŭ koruso kantos

   • the main clause
   • a choir will also sing

So the overall pattern is:

• Besides the fact that X will happen, Y will also happen.

That is a useful pattern to recognize in Esperanto.