Someone can ask you a question like this: Why did you do that?
You could answer: Because I wanted to do it!

Other example:
Why is the house so dirty?
Because the children had a food fight.

You can also use "because" in a complete sentence, to link the cause and effect relationship.

Example:
The house is so dirty because the children had a food fight.

To use “because” as a preposition, add “of”, to form “because of”. In this case, "because of" would modify the noun, not the verb, as in the previous cases.

Example:
The house was dirty because of the food fight.

SO can also be an adverb that intensifies the meaning of an adjective. In this case, we use the pattern SO + adjective and it means “tan” or “muy.”

Example:
I'm so tired.

SO may appear as "soooooooo" in writing. It is simply to avoid a silence or to give the speaker time to think about how to continue their conversation.

Example:
I was thinking we could go to the store sooooo…

SO is to mean “to (do something).” It is a short form of so that. The reason we can omit that is because what follows that is a complete sentence with a subject and a verb (and sometimes an object).

Example:
She left work early so/so that she could visit her mother.

SO is "then," but it can also be translated as "asi que." In this case, it works like a conjunction that joins two ideas or sentences.

Example:
It’s getting dark, so we will rest for the night.