Freedom of speech is an abstract concept related to an individual's inherent right to speak out openly and freely without any censorship or fear of repercussions in case of saying something that is deemed inappropriate by an arbitrary observer. Freedom of speech gained popularity in recent times as it's been adopted by more and more nations, moving away from the cumbersome censorship model and giving way to a system that truly benefits everyone. However, freedom of speech still has its limitations which are sometimes conveniently ignored by people.
One of the most important things to note is that freedom of speech is still subject to limitations related to other rights humans have. One's speech must not violate any inherent human rights, and it must not be openly opposed to a group or belief - something which classifies as "hate speech" in most cases. Some individuals have notoriously attempted to use freedom of speech as an excuse for being allowed to openly speak up against minorities, though this has normally been dealt with by their respective communities.
Freedom of speech is a concept that's not limited to speech, but also extends to other forms of expression, such as art. Art is actually even more free and forgiving in its definition of free speech, as it's more open to subjective interpretation and thus harder to claim a particular meaning has been instilled in some work. However, there still are some rules by which artists need to adhere.