El ensayo técnico prepara el ensayo general.

Yes—ensayo can mean essay in some contexts, but here it means rehearsal.

Spanish ensayo has more than one meaning:

• ensayo = essay
• ensayo = rehearsal
• in some technical/scientific contexts, it can also mean test or trial

In this sentence, because of técnico and general, it clearly refers to theatre or performance rehearsals:

• ensayo técnico = technical rehearsal
• ensayo general = dress rehearsal / final full rehearsal

Because both are specific singular masculine nouns.

• el ensayo técnico = the technical rehearsal
• el ensayo general = the dress rehearsal / general rehearsal

In Spanish, it is very normal to repeat the article before each noun phrase. You would not normally leave out the second el here.

Prepara is the third-person singular present tense of preparar.

That means it can translate as:

• prepares
• is preparing, depending on context

Here the subject is el ensayo técnico, which is singular, so the verb must be singular too:

• el ensayo técnico prepara
• literally: the technical rehearsal prepares

Spanish uses the simple present more often than English does, so the exact English translation depends on context.

Because the subject is singular:

• el ensayo técnico = singular
• therefore the verb is singular: prepara

If the subject were plural, you would use preparan:

• Los ensayos técnicos preparan el ensayo general.
• The technical rehearsals prepare the dress rehearsal.

Because el ensayo general is the direct object, and it is a thing/event, not a person.

Spanish uses the personal a mainly before specific people (and sometimes pets or personified beings), for example:

• Veo a María.
• I see María.

But here:

• prepara el ensayo general
• no a, because ensayo general is not a person

Because in Spanish, adjectives often come after the noun.

So:

• ensayo técnico = technical rehearsal
• ensayo general = general rehearsal

This is one of the most common word-order differences from English. English usually puts adjectives before the noun; Spanish often puts them after.

No, not normally. That word order would sound wrong in standard Spanish.

The natural form is:

• ensayo técnico
• ensayo general

Some adjectives can go before the noun in Spanish, but these two are not normally used that way here.

Usually, yes. In theatre and performance contexts, ensayo general is the final full rehearsal before the public performance.

In many cases, the best English equivalent is:

• dress rehearsal

But literally it is:

• general rehearsal

So depending on the context, both translations may be possible.

Ensayo técnico is a technical rehearsal.

It is the rehearsal focused on technical elements such as:

• lighting
• sound
• stage changes
• cues
• microphones
• projections

So the sentence suggests that this technical rehearsal helps get everything ready for the later ensayo general.

Because it is just a normal adjective here, not part of a proper name.

In Spanish, adjectives are not capitalized unless they begin a sentence or are part of a title/name that requires capitals. So:

• el ensayo general
• el ensayo técnico

all stay in lowercase in normal writing.

Yes, it is a cognate, and the meaning is related. But here ensayo general is a fixed expression in performance contexts.

It does not mean general in the sense of vague or unspecific. Instead, it means something like:

• overall
• full
• complete

So ensayo general is the rehearsal where the whole performance is run through.

Yes, Spanish word order is more flexible than English, but the original order is the most neutral:

• El ensayo técnico prepara el ensayo general.

You could move things around for emphasis, but that would be less neutral. For example:

• El ensayo general lo prepara el ensayo técnico.

This puts more focus on el ensayo general, but it is less straightforward for a learner. The original sentence is the best standard version.

In Spain, ensayo is pronounced approximately like en-SA-yo.

A rough guide:

• en as in ten, but with a clearer Spanish e
• sa
• yo with y sounding like the Spanish consonant in yo

The stress is on the middle syllable:

• en-SA-yo

Because Spanish often expresses relationships more directly than English does.

English might say something like:

• The technical rehearsal prepares for the dress rehearsal
• The technical rehearsal gets things ready for the dress rehearsal

But Spanish can simply say:

• prepara el ensayo general

That structure is normal and concise in Spanish. English sometimes needs an extra phrase such as for to sound natural, while Spanish does not.