Briefly: Freedom of speech, religion, of the press, and of assembly; right to petition
Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
In essence, it prohibits demonstrators from speaking out if the secret service is present. For instance, you can't shout dissenting speech at David Axlerod as he walks by because he's protected by the secret service.
Looks to me like no-free-speech zones became mobile with this bill.