Learn Spanish (Latin America): Yo soy de Colombia y soy profesor.

In Spanish, subject pronouns like yo (I) are usually optional because the verb itself tells us who is doing the action. Soy always means "I am". Using yo at the beginning is fine to start the sentence clearly or for emphasis, but repeating it as y yo soy profesor sounds unnatural, so native speakers drop the second one.

How does soy de translate to "I am from"?

The verb ser is used to talk about origins and identity. The preposition de means "of" or "from". When you put them together, soy de Colombia tells the listener your origin, translating perfectly to "I am from Colombia".

Why isn't there a word for "a" before profesor?

In English, we say "I am a teacher", but in Spanish, you do not use the words un or una (a/an) when stating your profession. You just use the verb directly followed by the job: soy profesor.

Why isn't the word profesor capitalized?

Unlike in English, Spanish does not capitalize words for professions, nationalities, or days of the week unless they happen to be the very first word in a sentence.