"We ask them what they want."
Translation:אנחנו שואלים אותם מה הם רוצים.
It's "על" or "אודות". Some other words like "בעניין" can also be appropriate.
We ask them about the book
אנו שואלים אותם על הספר
אנו שואלים אותם אודות הספר
אנו שואלים אותם בעניין הספר
Thank you, and how do the three differ from each other ? (even in the slightest way..)
They're similar enough that you won't be wrong in using any of them in any situation.
The word על is most common, while אודות is slightly more literary, but it's common to see "אודות החברה" or "אודותינו" on corporate websites where "about us" would be in English. The last one, בעניין, is kind of slangy, because the word עניין (matter) can be used as a stand-in for anything.
FOR A CONDITIONAL CLAUSE, I THINK "THAT YOU ARE CORRECT" the preposition you is preceded by ש. Why is that not the case for "they" in "what they want?"
That vs What ש vs מה
The pronoun "that" precedes a statement of fact, which you may think is true or false. The Hebrew equivalent is the word אשר, or its short form - the prefix ש.
The pronoun "what" precedes a pronoun clause, which takes the place of the noun. In this case the noun is a question - the question that we asked them. The Hebrew equivalent is מה.