[Rusty]

Hi! Welcome to the forums!

Originally Posted by chococakerella

This is a very successful area of study with excellent job opportunities in multiple countries.
Esto es un muy exitoso área de estudio con trabajo oportunidades excellente en múltiple países.

I don't believe there's a reason to begin the Spanish sentence with esto. This is a neuter form of the demonstrative pronoun reserved for abstract nouns/ideas. The topic (in omitted material) must have had something to do with "the area of study" that you proceed to talk about, so it must be a particular thing instead. The appropriate demonstrative pronoun needs to agree in gender and number with that Spanish noun. If the topic was área, for example, esto would need to be changed to esta, because that is the singular feminine form.
Next, the adverb/adjective pair you chose needs to follow the word it modifies, so place the pair after área de estudio. (The phrase as a whole is being considered as the noun being modified.)
Now, let's look at the article that precedes área. Even though the feminine indefinite article 'una' is indicated for use with a feminine noun, there's a rule in Spanish that singular, feminine nouns beginning with a stressed 'a' sound take the masculine form of the article, so 'un' is correct! Note that this rule only applies to the article, and only when it immediately precedes the noun. If the plural form of the feminine noun is used, the special-case rule no longer applies.
After the topic (área de estudio), you now should fix the adjective in the adverb/adjective pair that I had you relocate. It can't be masculine, since the noun it modifies is feminine.
Next, I see that you've translated the English construction 'with job opportunities' as is. The preposition is correct! But the back-to-back nouns are not. In English, the first noun is modifying the second. What kind of opportunities? Job opportunities. Since 'job' is being used here to modify 'opportunities', it is called an adjunct by English grammarians (since it no longer functions as a noun). While this structure is perfectly good English, Spanish uses a different construction! To make it right, you need to place the adjunct after the second noun AND insert the preposition de in between the two nouns. I also think empleo is the better word to use instead of trabajo, but both are seen. So, con oportunidades de empleo (or oportunidades de trabajo) is what you should now have.
One word remains in the prepositional phrase; it's the adjective you correctly placed after the noun. However, you wrote excellente, a misspelling.
What is excellent? The opportunities are excellent. In Spanish, adjectives agree in gender and number with the noun they modify. The Spanish noun in this case is plural, and feminine. The adjective needs to agree, on both counts.
Finally, let's have a look at the last prepositional phrase. There you have a plural object of the preposition, países. Good job on the spelling!
You chose to use the adjective 'multiple' in English. You can use the equivalent in Spanish, but might I suggest that the meaning of 'several' or 'many' would be better communicated with a form of mucho? Whichever you choose, make sure it agrees in gender and number with the noun.

Whew!! That's all for now!

Have a look at your other sentences to see where improvements might be made based on the discussion above, and post a revision so that we can offer further help. Consider using the word empleo or trabajo throughout. That other word you chose isn't correct!