El prelavado incluye el remojo.

Because both prelavado and remojo are masculine singular nouns in Spanish, so they take the definite article el.

• el prelavado = the prewash
• el remojo = the soaking / soak

This is one of the first things English speakers notice: Spanish usually uses articles more often than English does, especially with nouns.

Prelavado is a noun, not a verb. It means prewash or pre-wash cycle.

It is built from:

• pre- = pre- / before
• lavado = wash / washing

So prelavado literally means something like pre-washing or prewash.

In appliance settings, product labels, and laundry instructions, prelavado is very common in Latin American Spanish.

Remojo is also a noun. In this sentence, it refers to soaking or the soak cycle/process.

This can be confusing for English speakers because English often uses to soak as a verb, but here Spanish is using the noun el remojo.

Compare:

• remojar = to soak or to moisten
• el remojo = the soaking / soak

So the sentence uses two nouns:

• El prelavado = the prewash
• incluye = includes
• el remojo = the soaking

Because incluye is the conjugated verb, while incluir is the infinitive.

The subject is El prelavado, which is third-person singular, so the verb must match it:

• incluir = to include
• incluye = includes

So:

• El prelavado incluye el remojo = The prewash includes soaking

If you used incluir, the sentence would be incomplete unless it followed another verb, such as:

• Debe incluir el remojo = It should include soaking

Because el remojo is a direct object, and it is a thing, not a person.

Spanish uses the personal a before specific people (and sometimes pets or personified beings), but not normally before things.

So:

• incluye el remojo = correct
• incluye a el remojo = incorrect

A native English speaker might expect a preposition because English sometimes uses one in similar expressions, but Spanish does not need it here.

Usually, el remojo sounds more natural here because it refers to the soaking step/process as a defined part of the cycle.

Including the article makes it sound like a specific feature or stage:

• incluye el remojo = includes the soak phase / soaking

Without the article, incluye remojo might appear in very compact product language or labels, but in a full sentence, el remojo is the more standard choice.

In Latin American Spanish, incluye is pronounced approximately like:

een-KLOO-yeh

A few helpful notes:

• The stress is on clu: in-CLU-ye
• The y sound in -ye is usually like an English y or a soft j/y sound, depending on the region
• It is three syllables: in-clu-ye

A rough pronunciation guide for the whole sentence:

el pre-la-VA-do in-CLU-ye el re-MO-ho

Because after incluye, Spanish usually wants a noun here when describing a feature, component, or stage of a process.

So:

• incluye el remojo = includes soaking / includes the soak cycle

Using remojar directly would not fit this sentence well, because remojar is an infinitive verb meaning to soak. You would need a different structure, such as:

• incluye la opción de remojar = it includes the option to soak
• sirve para remojar = it serves for soaking / it is used to soak

In your original sentence, the speaker is naming a process step, so the noun remojo is the natural choice.

Not very often in casual conversation, but it is very natural in:

• laundry instructions
• appliance settings
• product descriptions
• manuals
• cleaning labels

It sounds like informative or technical everyday Spanish, especially in a household context.

For example, you might see similar phrases such as:

• El ciclo incluye enjuague.
• El programa incluye secado.
• El lavado incluye prelavado.

So while the sentence is not especially conversational, it is absolutely normal Spanish.

Yes, but the original order is the most neutral and natural:

• El prelavado incluye el remojo.

You could change the order for emphasis, but it would sound less neutral:

• El remojo lo incluye el prelavado.
  This is grammatically possible, but much less common and more marked.

For a learner, the standard pattern to remember is:

[subject] + [verb] + [direct object]

So:

• El prelavado = subject
• incluye = verb
• el remojo = direct object

That is the clearest and most natural order here.