Is it true that the constitution allows you to say what's you want?

Answer: Yes for the most part

Explanation: We have freedom of speech under the first amendment but if we threaten using that freedom, let's say we threaten a person or we threaten national

Security, that's when our speech isn't protected and we can face consequences like going to court

The freedom of speech guarantee in the Constitution doesn't give you the right to say anything you want, anywhere you want. The first amendment makes it unconstitutional for government to suppress speech (and expression as it's come to include).