Desciframos el símbolo e investigamos el compartimento.

Spanish changes y to e before a word that begins with an i sound. Since investigamos starts with that sound, e investigamos is the correct form.

This is just a pronunciation rule to avoid the awkward sequence y i....

Examples:

• padre e hijo
• siete e incluso ocho

But you keep y before words like hielo, because that starts with a y sound, not a pure ee sound.

It can mean either one.

For regular -ar verbs, the nosotros form is identical in:

• the present indicative
• the preterite

So:

• desciframos = we decipher / we deciphered
• investigamos = we investigate / we investigated

Context tells you which meaning is intended:

• Ahora desciframos el símbolo = We are deciphering / we decipher the symbol now
• Ayer desciframos el símbolo = We deciphered the symbol yesterday

Because Spanish often leaves subject pronouns out when the verb ending already shows the subject clearly.

Both desciframos and investigamos are we forms, so nosotros is not necessary.

You could say Nosotros desciframos el símbolo e investigamos el compartimento, but that usually adds emphasis, contrast, or clarity rather than being required.

The infinitives are:

• descifrar
• investigar

In the sentence, both are in the first-person plural form, meaning we.

They are both regular -ar verbs in this form.

Because símbolo and compartimento are both masculine singular nouns, and each one needs its own article:

• el símbolo
• el compartimento

So the sentence is literally:

• we decipher the symbol and investigate the compartment

If they were indefinite, you would use:

• un símbolo
• un compartimento

Because the stress falls on the first syllable: SIM-bo-lo.

Símbolo is an esdrújula word, which means the stress is on the third-to-last syllable. In Spanish, all esdrújula words take a written accent mark.

So the accent is there to show the correct stress.

In standard Peninsular Spanish, it is pronounced roughly dess-thee-FRA-mos.

A few key points:

• the stress is on FRA
• the c before i sounds like th in thin in most of Spain
• the r in fra is a light tap

So descifrar in Spain sounds different from many Latin American pronunciations, where that c would sound like s.

In standard Spanish, no.

Before investigamos, the correct conjunction is e, because the next word begins with an i sound.

So:

• correct: e investigamos
• not standard here: y investigamos

Yes, usually very similarly.

Compartimento refers to a separate section or enclosed part within something larger, such as:

• a train compartment
• a storage compartment
• a battery compartment

So it is a fairly concrete, physical word. It sounds more specific than general words like espacio or lugar.

Yes. Spanish word order is more flexible than English, especially when joining two clauses with y/e.

For example, you could also say:

• Investigamos el compartimento y desciframos el símbolo

That changes the order of the actions, and because the second clause now begins with desciframos, the conjunction goes back to y, not e.

The original sentence sounds natural and presents the actions in sequence:

1. we decipher the symbol
2. we investigate the compartment