In what ways can you use "lo" in Spanish.
My friend and I were discussing how to translate and understand LO as it comes in front of adjectives, que, and how to properly understand it in English. I wanted to see the different uses you can come up with.
5 Answers
Me da lo mismo.
It's all the same to me. "Lo mismo" = the same thingLo mejor es ser franco.
It's best to be honest. "Lo mejor" = the best thingLo pasado, pasado está.
What is past, is past. (Let bygones be bygones.) "Lo pasado" = what is pastLo poco agrada y lo mucho enfada.
A little is pleasing but a lot is annoying. (Too much of a good thing is bad.)
"Lo poco/lo mucho" = what is few/what is excessiveLa posesión es lo que cuenta.
Possession is what counts. (Possession is 9/10 of the law.) "Lo que" = the thing that....Lo que es moda no incomoda.
What is fashion does not inconvenience. (We're willing to put up with a lot of discomfort for the sake of fashion.)
"Lo que" = what; that which
In all these instances, "lo" can be considered as "the thing that...." -- an otherwise nonspecific object or concept which is only specified by the rest of the phrase or sentence. Without it's context "lo" would be null, totally meaningless.
So, "lo" seems to be unique amongst the articles. Other articles (el, la, los, las, un, una, unas, unas) precede and define a noun. I don't believe that they ever precede an adjective which does not subsequently refer to a noun, but "lo" can. When "lo" does precede an adjective, it becomes part of an abstract noun phrase... "the thing that" is described or specified by the adjective.
And that's not all! "Lo" can also be used as an adverb to modify an adjective... but that will have to wait for another post.
OK, not Lazarus by a long shot..... but I gave it my best! 
The list might be shorter if you asked, "In what ways can you NOT use 'lo'...."!!
Since this is what I'm currently studying (articles & pronouns) I'd be happy to play, but will someone please correct me if (better make that when) I'm wrong?
Amor con amor se paga; y lo demás con dinero.
(Love is repaid with love; and the rest with money.)Here lo is used as the neuter article to represent part of something as it relates to the whole. "Lo demás" = "the rest" like "lo mejor" or "lo peor" = the best/the worst.
But "demás" is an adjective, not a noun, so it can't be strictly interpreted as "the remainder" or "the rest." It must be "lo demás" = the part remaining.
Borra con el codo lo que escribe con la mano.
He erases with his elbow what he is writing with his hand.
"Lo que" = las cosas que = the things that..... Neuter article representing "the things that" or "those things that" or "that which." What those things are is not important (a generality of sorts), but they are specified as "the things that he is writing."
I had to look in my dictionmary for this 
lo artículo determinado
1 (con adjetivos) the… thing
Lo interesante/difícil es… / The interesting/difficult thing is…
lo salado/bueno savoury / good things
En lo físico se parece a mí. / Physically, he is like me.
2 (uso enfático, en exclamaciones)
¿Has visto lo cara que está la vida allí? / Did you see how expensive everything is over there?
¡Es increíble lo poco que cuesta! / I can’t believe how cheap it is!
lo pronombre personal 1 (él) him
Lo eché de casa. I threw him out.
2 (cosa) it
¿Dónde lo tienes? / Where is it?
No me lo creo. / I don’t believe it.
NOTA Cuando lo se usa como complemento directo de algunos verbos como decir, saber y ser no se traduce
Te lo diré mañana. / I’ll tell you tomorrow.
Todavía no eres médico pero lo serás. / You’re not a doctor yet but you will be one day.
Amable sí que lo es. / He’s undoubtedly very nice.
3 (usted) you
Lo veo cansado. / You look tired.
LOC - lo cual / which
lo cual no es cierto / which isn’t true
lo de…
1 (posesión)
Lo de Juan está ahí. / Juan’s things are over there.
2 (asunto)
Lo del viaje fue muy inesperado. / The journey came as a real surprise.
Lo de ayer fue un desastre. / What happened yesterday was a disaster.
lo de que…
En esa carta me comentabas lo de que Pedro no está de acuerdo. / You mentioned in your letter that Pedro is against it.
Lo de que la tirasen a la piscina vestida no tuvo ninguna gracia. / Throwing her into the pool fully dressed just wasn’t funny.
lo mío
1 (posesión) my, your, etc. things
Todo lo mío es tuyo. / All I have is yours.
2 (afición) my, your, etc. thing
Lo suyo es la música. / Music’s his thing.
lo que… what
No te imaginas lo que fue aquello. / You can’t imagine what it was like.
Haré lo que digas. / I’ll do whatever you say.
Haría lo que fuera por aprobar. / I’d do anything to pass!
That's a huge question. Try the dictionary entry here.
