El temperamento afecta a la compatibilidad.

Because afecta is the third-person singular present tense form of the verb afectar.

• afectar = the infinitive, to affect
• afecta = it affects / affects

In this sentence, the subject is El temperamento, which is singular, so the verb must also be singular:

• El temperamento afecta... = Temperament affects...

If you used afectar, the sentence would be ungrammatical here because Spanish needs a conjugated verb in a normal statement.

In Spanish, afectar is commonly followed by a before the thing being affected:

• afectar a alguien
• afectar a algo

So:

• El temperamento afecta a la compatibilidad.

This is just the normal pattern of the verb. English says affect something, but Spanish usually says afectar a algo.

This a is not the same as the personal a used only with people. Here it is part of how the verb is often used.

Spanish uses definite articles much more often than English does, especially when talking about things in a general sense.

So Spanish naturally says:

• El temperamento afecta a la compatibilidad.

Even though in English you might say simply Temperament affects compatibility, Spanish usually keeps the articles:

• el temperamento
• la compatibilidad

Leaving them out would usually sound unnatural in a sentence like this.

Because el here shows grammatical gender, not biological sex.

In Spanish, every noun is grammatically masculine or feminine. Temperamento is a masculine noun, so it takes el:

• el temperamento

That does not mean temperament is male. It is just the grammatical category of the noun.

Compatibilidad is feminine because nouns ending in -dad are almost always feminine in Spanish.

So:

• la compatibilidad
• la realidad
• la ciudad
• la posibilidad

This is a very useful pattern to remember.

Yes, it is in the present tense: afecta.

Here, the present tense is being used for a general truth or general statement, not necessarily for something happening right this second.

So the idea is:

• Temperament affects compatibility in general.

Spanish uses the present tense for this kind of statement just like English does.

The subject is El temperamento.

That is the thing doing the action. The verb is afecta, and the thing receiving the effect is la compatibilidad.

So the structure is:

• El temperamento = subject
• afecta = verb
• a la compatibilidad = object/complement affected by the verb

A good rough breakdown is:

• Temperament = what affects
• affects
• compatibility = what is affected

Yes, absolutely. That is a very natural alternative.

• afectar a = to affect
• influir en = to influence

So:

• El temperamento afecta a la compatibilidad.
• El temperamento influye en la compatibilidad.

Both are correct, but there is a slight nuance:

• afectar can sound a bit more direct
• influir en can sound a bit softer or more like has an influence on

Both are common and natural.

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

• El temperamento afecta a la compatibilidad.

Spanish word order is often flexible, but changing it can alter the emphasis or make the sentence sound more formal or marked.

For example:

• A la compatibilidad la afecta el temperamento.
  This is grammatical, but much less neutral and sounds emphatic.

A more common alternative would be a passive-style structure:

• La compatibilidad se ve afectada por el temperamento.
  = Compatibility is affected by temperament.

So yes, word order can change, but the original version is the simplest and most standard.

The stress is on the final syllable -dad:

• com-pa-ti-bi-li-DAD

A rough English-friendly guide would be:

• kom-pah-tee-bee-lee-DAD

And the full sentence is pronounced roughly like:

• el tem-pe-ra-MEN-to afek-TA a la kom-pa-ti-bi-lee-DAD

Main stresses:

• tem-pe-ra-MEN-to
• afec-TA
• compatibili-DAD

Not exactly. They are related, but they are not identical.

• temperamento = temperament, natural disposition, emotional makeup
• personalidad = personality, broader overall character

So temperamento often refers more to someone’s innate or emotional tendencies, while personalidad is broader.

Depending on context, both words might fit, but they are not always interchangeable.

You may sometimes see or hear this, especially in some contexts, but for learners it is best to treat afectar as normally taking a before its object:

• afecta a la compatibilidad

That is the safest and most standard choice for this sentence.

So if you are producing Spanish yourself, use:

• El temperamento afecta a la compatibilidad.

Because verbs agree with the subject, not with the noun that comes after them.

Here the subject is:

• El temperamento = singular

So the verb must be singular:

• afecta

It does not matter that la compatibilidad is feminine. Gender does not change the verb form in Spanish, and this noun is not the subject anyway.

If the subject were plural, then the verb would change:

• Los temperamentos afectan a la compatibilidad.

So the verb agrees with temperamento, not with compatibilidad.