El dolor era terrible.

Because dolor is a noun, and here Spanish uses the definite article: el dolor = the pain.

In this sentence, it refers to a specific pain already understood from the context. Spanish often uses articles more regularly than English does, especially with nouns used as the subject of a sentence.

So:

• El dolor era terrible = The pain was terrible
• Leaving out el here would sound ungrammatical in normal Spanish.

Yes. Dolor is a masculine noun, so it takes el, not la:

• el dolor
• not la dolor

That is something you simply have to learn with the noun. The ending -or is often masculine, but not always, so it is best to learn nouns together with their article.

Era is the imperfect form of ser for he/she/it and you (formal).

So:

• yo era = I was
• él/ella era = he/she was
• el dolor era = the pain was

In this sentence, era means was.

This is the classic imperfect vs preterite question.

Era gives a description or background. It presents the pain as an ongoing state or circumstance in the past.

• El dolor era terrible = the pain was terrible / the pain felt terrible

Fue would present it more as a complete, finished whole.

• El dolor fue terrible = the pain was terrible, seen as a completed event or episode

A simple way to remember it:

• era = descriptive, ongoing, background
• fue = completed, bounded, seen as a whole

So if you are describing what things were like at that time, era is very natural.

Because terrible here describes the pain itself: what it was like.

Spanish normally uses ser for that kind of description with a noun like dolor:

• El dolor era terrible

Using estar here would sound unusual or unnatural in standard Spanish. Estar is more often used for states or conditions of people and things in other contexts, but with dolor, ser terrible is the normal pattern.

Compare:

• El dolor era terrible = The pain was terrible
• Tenía un dolor terrible = I had a terrible pain
• Estaba fatal = I felt awful

So the sentence is using the standard and natural choice.

Because terrible is one of the many adjectives that end in -e, and those usually have the same form for masculine and feminine singular.

So:

• el dolor terrible
• la noticia terrible

Both use terrible.

It only changes in the plural:

• el dolor terrible
• los dolores terribles

Usually yes, but the exact nuance depends on context.

With pain, terrible often means:

• awful
• very bad
• severe
• intense

So in this sentence, it does not necessarily mean morally terrible or shocking. It simply means the pain was very strong or awful.

Yes, but El dolor era terrible is the most neutral and natural order.

Spanish can sometimes change word order for emphasis or style, for example:

• Era terrible el dolor

That sounds more literary or dramatic. A learner should stick with:

• El dolor era terrible

because it is the standard, straightforward version.

A simple pronunciation guide is:

el do-LOR E-ra te-RRI-ble

A few key points:

• dolor is stressed on the last syllable: do-LOR
• era is stressed on the first syllable: E-ra
• terrible is stressed on rri: te-RRI-ble
• the rr in terrible is a rolled or trilled r

So the rhythm is:

el do-LOR E-ra te-RRI-ble

Yes, absolutely. That is also very natural Spanish.

The difference is mainly in focus:

• El dolor era terrible describes the pain
• Tenía un dolor terrible means I had a terrible pain or He/She had terrible pain, depending on context

So both are correct, but they are built differently:

• El dolor era terrible = subject is the pain
• Tenía un dolor terrible = subject is the person who had the pain

Both are common and useful.