In addition to the definite and
indefinite articles, Spanish has what is called a
neuter article. This article, lo, is invariable and
is used in front of just about any adjective in order to express something
abstract or a quality.
the easy thing, part
the good thing
what is just
the best part
Lo + adjective is usually
translated in English as
The adjective thing/part/one/style
or What is adjective. For example,
Lo difícil es que no comprendo la diferencia.
The hard thing is that I don't understand the difference.
No viste lo mejor de la película.
You didn't see the best part of the movie.
Lo importante es que estamos juntos.
What's important is that we are together.
Me gusta lo azúl.
I like the blue one.
Vestís a lo americano.
You dress in the American style/like Americans.
The construction lo + adjective + que