Definition - What does First Amendment mean?
The First Amendment is an amendment in the U.S. Constitution, which grants all American citizens the right to the freedom of speech, expression, assembly, religion, and "to petition the government for a redress of grievances". The First Amendment also prohibits congress from making any laws that respect an establishment of religion. This amendment is the first in the Constitution among many that grant U.S. citizens rights.
Justipedia explains First Amendment
The First Amendment is basically just a constitutional amendment that lays out a number of primary freedoms that American citizens are entitled to. In America, there are many different newspapers, religions, assemblies, television shows, etc. All of these are granted their right to exist in the country by the First Amendment. Without the First Amendment, Americans might not have been able to enjoy the freedom of speech, religion, assembly, etc.