Mia patro diras, ke ovo kun salo estas pli bona ol pano kun sukero.

Ke means that and introduces a subordinate clause.

So the sentence is built like this:

• Mia patro diras = My father says
• ke ovo kun salo estas pli bona ol pano kun sukero = that egg with salt is better than bread with sugar

It works very much like English that in a sentence such as My father says that...

Usually, no. In normal Esperanto, ke is normally kept.

English often says My father says egg with salt is better..., leaving out that. Esperanto usually does not do that. You would normally say:

Mia patro diras, ke ...

So for a learner, it is best to think: if Esperanto needs that to introduce a full clause after a verb like say, know, think, hope, etc., use ke.

Because mia patro is the subject of diras.

In Esperanto, the -n ending marks the direct object. Here, my father is the one doing the saying, so he is the subject, not the object.

• Mia patro diras = My father says
• Mi vidas mian patron = I see my father

In the second example, mian patron has -n because he is the object of vidas.

Because Esperanto uses la only for something definite, roughly like English the.

Here the sentence is talking more generally, not about one specifically identified egg or one specifically identified bread. So no la is needed:

• ovo = egg / an egg
• pano = bread / a bread item, depending on context

If you said la ovo, that would mean the egg, a specific egg already known from context.

By itself, ovo can mean egg or an egg, depending on context. Esperanto has no separate indefinite article like English a/an.

So:

• ovo = egg / an egg
• la ovo = the egg

In this sentence, the meaning is more general, so English may translate it in a slightly more natural way depending on context, but grammatically Esperanto simply uses the bare noun ovo.

Because kun means with.

So:

• ovo kun salo = egg with salt
• pano kun sukero = bread with sugar

Also, after a preposition like kun, the noun normally stays in its basic form, so:

• kun salo, not kun salon
• kun sukero, not kun sukeron

That is because the preposition already shows the relationship.

This is the normal Esperanto pattern for comparisons:

• pli = more
• bona = good
• ol = than

So:

• pli bona = better literally more good
• pli bona ol = better than

Examples:

• Tio estas pli bona. = That is better.
• Tio estas pli bona ol ĉi tio. = That is better than this.

So in your sentence:

ovo kun salo estas pli bona ol pano kun sukero
= egg with salt is better than bread with sugar

Because bona is describing a singular subject and it is not a direct object.

Here, ovo kun salo is singular, so the adjective is singular too:

• ovo ... estas bona = egg ... is good

It is not bonan because there is no direct object here. After estas, you usually have a description, not a direct object.

Compare:

• La ovo estas bona. = The egg is good.
• Mi manĝas bonan ovon. = I eat a good egg.

In the second sentence, bonan ovon gets -n because it is the direct object of manĝas.

The ending -as marks the present tense in Esperanto.

So:

• diras = says / is saying
• estas = is / are / am

Esperanto verbs do not change form for different persons:

• mi diras = I say
• vi diras = you say
• li diras = he says

The same diras works for all persons. That is much simpler than English.

Esperanto word order is fairly flexible, but the version here is the most neutral and natural.

Standard order:

Mia patro diras, ke ovo kun salo estas pli bona ol pano kun sukero.

Because Esperanto has clear endings and function words, some rearranging is possible for emphasis. But as a learner, the safest choice is the normal pattern:

• subject
• verb
• subordinate clause
• inside that clause: subject + verb + comparison

So this sentence is a very good model to follow.

Because Esperanto often uses a comma before a subordinate clause introduced by ke.

So:

Mia patro diras, ke ...

This comma helps show that the second part is a clause depending on the first part. You will often see this with ke, ĉar, se, and similar words.

Even if punctuation habits vary a little, using the comma here is completely normal and recommended for learners.