What exactly does procedural law mean?

In our country, the so-called criminal defense lawyer procedure law is the criminal procedure law, which is formulated to ensure the smooth implementation of the criminal law (substantive law). The Criminal Procedure Law stipulates in detail the rights and obligations of lawyers at different stages of criminal proceedings. According to these regulations, lawyers can successfully carry out various legal work in combination with the Lawyers Law. For example, as stipulated in the Criminal Procedure Law, a criminal suspect may hire a lawyer to provide him with legal advice, legal services of acting as an agent to appeal and accuse him from the day when compulsory measures are taken or he is interrogated by the public security organ for the first time; For another example, hired lawyers can apply for bail pending trial for criminal suspects in custody. However, in order to maintain the principle of "taking facts as the basis and law as the criterion", the Criminal Procedure Law also stipulates that lawyers shall not instruct criminal suspects in custody to collude or help them destroy evidence.