Mi volas, ke infanoj respektu unu la alian.

Ke means that and introduces a subordinate clause.

So:

• Mi volas = I want
• ke infanoj respektu unu la alian = that children respect one another

Esperanto often uses ke where English may or may not use that. In English, I want children to respect each other is more natural than I want that children respect each other, but in Esperanto the ke clause is a normal way to express this idea.

Respektu is the -u form, often called the volitive or jussive form. It is used for wishes, commands, requests, and desired actions.

Here, the speaker is expressing a wish or desire about what the children should do:

• Mi volas, ke infanoj respektu... = I want children to respect...

If you said respektas, that would mean respect as a plain statement of fact:

• Mi volas, ke infanoj respektas unu la alian would sound wrong, because after Mi volas, ke..., Esperanto normally uses -u when the clause expresses something wanted or desired.

Not directly. It is not the same as speaking straight to them and saying Respektu unu la alian! = Respect one another!

In this sentence, respektu appears inside a ke clause after Mi volas, so it expresses what the speaker wants to happen:

• I want children to respect each other

So it is a desired action, not a direct command addressed to infanoj.

Without la, infanoj means children in a general sense.

• infanoj = children / children in general
• la infanoj = the children / specific children

So this sentence most naturally means something like:

• I want children to respect one another
• I want kids to respect each other

If you meant a particular group, you could say:

• Mi volas, ke la infanoj respektu unu la alian.

Unu la alian is the standard Esperanto expression for each other or one another.

Literally, it is built from:

• unu = one
• la alian = the other

Together, the idea is reciprocal: each one does the action toward the other(s).

So:

• Ili amas unu la alian. = They love each other.
• Infanoj respektu unu la alian. = Children should respect each other.

Even though it looks a little unusual at first to an English speaker, it is a very common and normal Esperanto pattern.

The -n marks the direct object.

Here, the verb is respektu = respect, and the people being respected are expressed by la alian.

So:

• unu la alia would not work here
• unu la alian is needed because the other is the object of respect

You can think of it this way:

• each one respects the other
• therefore the other must be in the accusative: alian

Because in this expression, only alia takes the object ending.

The fixed reciprocal pattern is:

• unu la alian = each other
• unu la alia = one another / each other only in a non-object role, depending on the sentence structure

In your sentence, the standard object form is unu la alian. Esperanto treats this as a set expression, and the accusative goes on alian.

Yes. A few alternatives are possible, though unu la alian is the most straightforward and standard here.

For example:

• Mi volas, ke infanoj reciproke respektu.
  = I want children to respect one another mutually.

This is grammatical, but unu la alian is usually more direct and common for learners.

You may also see other reciprocal expressions in other contexts, but for each other, unu la alian is the safest everyday choice.

Because Esperanto usually does not copy the English pattern I want children to respect each other with a bare infinitive in the same way.

The normal Esperanto structure is:

• Mi volas, ke infanoj respektu unu la alian.

That is, Esperanto prefers:

• I want that ...
• followed by a ke clause
• with the verb in the -u form

So although English uses want + object + infinitive, Esperanto typically uses volas, ke...

It breaks down like this:

• Mi = I
• volas = want
• ke = that
• infanoj = children
• respektu = should respect / respect (as something desired)
• unu la alian = each other / one another

So the structure is:

• main clause: Mi volas
• subordinate clause: ke infanoj respektu unu la alian

This is a very common Esperanto pattern:

• Mi esperas, ke ŝi venu. = I hope that she comes / will come.
• Li postulas, ke ni faru tion. = He demands that we do that.