"Do you want to buy butter?"
Translation:¿Quieres comprar mantequilla?
It depends... in Spanish you determine general or specific by context...
If you say at the supermarket: "¿Quieres comprar LA mantequilla?" you are referring to a determined butter. When you write the same sentence WITHOUT "LA" you are talking about any butter in general.
If you say "LA mantequilla tiene mucha grasa" (Butter has a lot of fat) you are talking about butter in general. Indeed it's the only way you can write that sentence in Spanish, you can't forget the article.
You could refer to a specific butter by saying "ESA mantequilla tiene mucha grasa"
If you want to make it in a generic sense, you can delete the article:
With this example you will see better:
Tengo libros aquí, I say that I have many books here, no matter what kind of books.
Tengo los libros aquí, I'm specifying that I have some concrete books here. Maybe some you're waiting for.
Every time I hear the word "mantequilla" I'm reminded of my seventh grade Spanish class twenty years ago--yes, I remember it well!--in which we had to listen to some audio recordings. One of the sentences was "Hay manteQUILLa en la SILLa." (Capitalization to show inflection.)
Twenty years later I cannot get it out of my head.
I am hoping by passing on the curse to you, it may peacefully exit my poor head.