El santo aparece en la pintura.

In Spanish, singular countable nouns usually need an article or another determiner. So el santo means the saint.

Saying just santo by itself would usually sound incomplete in a normal sentence like this.

• el santo = the saint
• un santo = a saint

Santo means saint. It is a masculine singular noun here.

Its feminine form is santa:

• el santo = the saint
• la santa = the female saint

You may also see San before the name of a male saint, for example San Juan, but that is a special naming form, not the same grammar pattern as this sentence.

Aparece is the third person singular present tense of aparecer, meaning to appear.

The subject is el santo, which is singular, so the verb must also be singular:

• yo aparezco = I appear
• tú apareces = you appear
• él/ella aparece = he/she appears
• el santo aparece = the saint appears

No. They are related in form but have different meanings.

• aparecer = to appear, to show up, to be visible
• parecer = to seem, to appear in the sense of giving an impression

So here aparece means the saint is shown or visible in the painting, not that the saint seems a certain way.

Spanish commonly uses en where English might sometimes use in or on, depending on context.

Here en la pintura means in the painting in the sense of within the image / represented in the artwork.

So Spanish naturally says:

• aparece en la pintura = appears in the painting

Even if English might sometimes say on the painting, Spanish still normally uses en.

Here pintura means painting, as an artwork.

Depending on context, pintura can also mean paint or painting as an art form, but in this sentence it clearly refers to the artwork itself.

Because pintura is feminine, it takes la:

• la pintura = the painting

This is a very normal Spanish word order:

subject + verb + prepositional phrase

• El santo = subject
• aparece = verb
• en la pintura = where/in what context the saint appears

Spanish word order is often flexible, but this version is the most neutral and straightforward.

Yes. That is also correct.

Spanish allows more flexibility than English with word order.
En la pintura aparece el santo puts more focus on en la pintura or sounds a bit more descriptive.

Both are grammatical:

• El santo aparece en la pintura.
• En la pintura aparece el santo.

The first one is the most basic, neutral pattern for learners.

There is no h in those words, so nothing special there.

A few pronunciation notes:

• santo: SAN-to
• aparece: in Spain, the c before e is usually pronounced like the th in think
  So it sounds roughly like apa-RE-the in much of Spain.
• In many Latin American accents, that same c sounds like s, so apa-RE-se.

Since you asked about Spanish from Spain, the Spain pronunciation is the one learners often aim for.

Because Spanish nouns have grammatical gender.

• santo is masculine, so it takes el
• pintura is feminine, so it takes la

So:

• el santo
• la pintura

This does not necessarily mean that the object itself is biologically male or female. It is just part of Spanish grammar.

Yes, depending on context. Aparecer can mean:

• to appear
• to show up
• to turn up
• to become visible

But in this sentence, because of en la pintura, the most natural meaning is that the saint is depicted / appears in the painting, not that he physically arrives somewhere.

Not exactly.

• aparece en la pintura focuses on being visible or represented in the painting
• está en la pintura sounds more like is in the painting, but it is less natural if you are talking about what is depicted in an artwork

So aparece is the better choice when describing what can be seen in an image or artwork.