HELP WILL GIVE! What does the author mean when they say, “...seven Southern states declared their secession.”?

It is written in the constitution saying all beliefs are allowed in the u.s. justice will be surved to everyone no matter what the color of that person is. and that all people are equal not matter there color is the u.s. that was a lie though because black people were still treated poorly, and there were places that was white people only such as hospitals, schools, bathroom, and more.

Is this a true or false?