PLS HELP What does “In the ruling for Cantwell v. Connecticut (1939; 9-0), the US Supreme Court held that state and local governments’ infringement upon religious freedom is also unconstitutional.” mean?

What reasons does the speaker provide to support his viewpoint or claim in what to the slave is the fourth of july i read to speech and but i just don't fully understand the question i just want to make sure i get it right so to explain that the question is asking me to do. and you!