Aprenderse el texto teatral ayuda al elenco.

Because aprenderse often means to learn something thoroughly / to learn it by heart / to memorize it.

With a play text, that nuance makes a lot of sense: the cast is not just studying the text, but really getting it into memory.

So:

• aprender el texto = to learn the text
• aprenderse el texto = to learn the text well, often to memorize it

In Spain, this pronominal use is very common with things like:

• aprenderse una canción
• aprenderse una lista
• aprenderse un papel
• aprenderse el guion

Not in the usual washing yourself / seeing yourself sense.

Here, se is part of a pronominal use of the verb. It changes the nuance of aprender, but it does not literally mean that someone is learning themself.

So in this sentence, aprenderse is best understood as a set expression meaning something like to get something learned / memorized.

This kind of se is very common in Spanish, and it often adds a sense of:

• completeness
• personal involvement
• doing something thoroughly

Because in Spanish, an infinitive can act like a noun or noun phrase.

So Aprenderse el texto teatral functions as the subject of the sentence:

• Aprenderse el texto teatral = the action of learning/memorizing the play text
• ayuda = helps
• al elenco = the cast

This is very normal in Spanish, just like in English we can say:

• Studying helps
• Reading is useful
• Memorizing the script helps the cast

Because the subject is the whole infinitive phrase Aprenderse el texto teatral, and that counts as singular.

In Spanish, an infinitive used as a subject normally takes a singular verb:

• Fumar es malo.
• Leer ayuda mucho.
• Aprenderse el texto teatral ayuda al elenco.

So even though elenco refers to several people, it is not the subject. The subject is the action aprenderse el texto teatral.

Al is the contraction of a + el.

The verb ayudar often takes a before a person or group being helped:

• ayudar a alguien

So:

• a + el elenco → al elenco

This contraction is mandatory with a + el:

• Voy al teatro = a + el teatro
• Ayuda al elenco = a + el elenco

The only common exception is when el is part of a proper name, like a El Escorial.

Elenco means cast: the group of actors in a play, film, or show.

In this sentence, el elenco is the theatrical cast.

In Spain, elenco is standard and natural, though depending on context you may also hear:

• reparto = cast
• compañía = company/troupe, sometimes referring to the theatrical group rather than just the actors

So el elenco is a good word here.

Literally, texto teatral means theatrical text or play text.

It is understandable and correct, but it sounds a bit more formal or literary than some other options.

Depending on context, Spanish speakers might also say:

• el guion = script
• el libreto = libretto / script, especially in certain performance contexts
• el texto = the text
• la obra = the play
• el papel = role/part, sometimes when talking about what an actor has to learn

For a stage play, texto teatral is fine, but in everyday speech many people might choose a more specific word depending on what exactly they mean.

Yes, that is grammatical.

The difference is mainly nuance:

• Aprender el texto teatral = learning the play text
• Aprenderse el texto teatral = learning it thoroughly, often memorizing it

If the idea is that actors need to know their lines well, aprenderse sounds especially appropriate.

So both are possible, but aprenderse fits the theatre context very well.

Because both nouns are presented as specific, identifiable things:

• el texto teatral = the particular play text being worked on
• el elenco = the cast involved

In Spanish, articles are used more often than in English, and leaving them out here would sound unnatural.

For example:

• Aprenderse texto teatral ayuda... sounds wrong
• Aprenderse el texto teatral ayuda... sounds natural

So the articles are important here.

Very often, yes.

When the thing being helped is a person or group of people, Spanish normally uses a:

• Ayudo a mi hermano.
• Esto ayuda a los estudiantes.
• Ayuda al elenco.

That is why al elenco appears here.

You may also see ayudar a + infinitive in other structures, such as:

• Ayuda a recordar el texto.
  = It helps to remember the text.

So a is a very common partner of ayudar.

Yes. Spanish allows some flexibility in word order.

For example, you could also say:

• Al elenco le ayuda aprenderse el texto teatral.

That version puts more focus on the cast, and le repeats the indirect object in a very natural Spanish way.

But the original sentence:

• Aprenderse el texto teatral ayuda al elenco.

is clear, neutral, and perfectly correct.

It starts with the action itself, which makes the sentence feel a bit like a general statement.