Why is the 5th amendment important?
Right to the "due process" of law.
Due to process of law to tell why are you arrested.
Say like if you were accused of a crime you didn't do and you were tried twice for it. It won't happen 'cause that would be a double jeopardy. For example if you steal something you can not be tried twice for the same crime unless you do it again. It's not fair to keep being tried twice for the same crime. That's why the fifth amendment is there to protect us from those kind of suff.
When you get arrested you need to know your rights.
When police arrest you that they must read you the miranda warning. For example if you are arrested and the police didn't tell you your rights and then they did something wrong. If thy do tell you rights you have the to not talk you have the right to talk by writing on paper or nodding as an answer. Those are the rights that would protect you of being guilty