I received a letter of development where I don’t agree with what the letter is saying and do not want to sign it. What are my rights am I allowed to speak to HR directly? If I don’t sign what are the consequences

If you do not agree with the letter, you should provide a written response indicating why you disagree (even in this scenario, you can sign the letter as long as it's just to acknowledge receiving it). You can certainly request to speak with HR and they should meet with you.