Modifiers Maybe?
I can't remember what kind of words these are grammatically and how they lend meaning to context.
Examples:
lo as in lo siento
que as in lo que se
le as in di le que vive en tu suenos
2 Answers
lo as in lo siento
Direct Object. Siento = I feel. Lo siento = I feel it/sorry.
que as in lo que se
Relative Pronoun. Lo que = the that/what. Lo que quiero decir es que eres mi buen amigo. What I want to say is that you are my good friend.
Lo que se itself doesn't have a meaning, I believe. Lo que se afeita - That which shaves itself, for example, makes more sense.
le as in di le que vive en tu suenos
Indirect Object. Di = Say. Di le = say to/tell him/her (actually written as 'dile). Dile que vive en tus sueños = Tell her that she lives in your dreams.
Hope I've helped. Check the Grammar section of this site for detailed coverage.
As far as I know, lo is a direct object pronoun, and le is an indirect object pronoun.