Answer:
In the excerpt, Justice Holmes is arguing, as he himself said " that whether the personal right of free speech can be infringed is a question of proximity and degree". In other words, free speech can be restricted if the speech is calling for the commitment of a crime.
In the case that brought the Court's decision, two members of the Socialist Party of the United States were convicted because they were distribuing flyers that opposed military drafting for World War I. Opposing the draft, or promoting opposition to it, was illegal under the Espionage Act of 1917, and the Supreme Court considered that those prohibitions were constitutional because the nation was at war.
To sum up, what Justice Holmes is saying is that expressing opposition to a war is a form of free speech, but promoting draft-dodging is not.