Answer:
Prevented the government from limiting people's free speech.
Step-by-step explanation:
Prior the Gitlow v. New York case, It is possible for legislators to passed various form of laws/orders that is designed to prevent the publics from voicing a certain opinion.
After the case was brought up to the supreme court, the court ruled that it is unconstitutional for a legislators to do that. Passing such legislations was seen as a serious violation of the US constitution which was designed to protect the freedom of speech.