[aniRB]

Hola,
Soy estudiante nueva de español.

I am only familiar with your first example of "lo" when an adjective is used as a noun, and there is no equivalent in English. The definite article would be used: "The good, the bad, the ugly."

I am also familiar with the use of "lo" as a neuter pronoun in the context of responding to a statement. Consider the following:
"Estás consado?"
"Sí, lo estoy."

In English, there is no "lo" equivalent. The response would either be "Yes" or "Yes I am" or "Yes I am tired."

I have no idea if this is helpful or if I am just telling you things you already know. Please let me know.

Hasta otra,
-ani