An arraignment in Nevada is a court hearing where the prosecution formally brings criminal charges against a defendant. It marks the beginning of a criminal case, and the prosecution gives to the defendant (or defense attorney) a copy of all their evidence in the case so far. This evidence is called "discovery."
If the defendant is facing misdemeanor charges, he/she enters an initial plea at the arraignment. Typically, defendants will enter a "not guilty" plea, and then the defense attorney and prosecution will try to hammer out a negotiation (plea deal) over the next several weeks or months. If they cannot agree, the defendant has the choice to go to trial.
Alternatively, if the defendant is facing felony charges, he/she can either enter a guilty plea or ask for a "preliminary hearing" to be scheduled in a few weeks. A preliminary hearing is like a mini-trial where the prosecution has to prove to the court that they have enough evidence to bring criminal charges and have an actual trial. During that time, the defense attorney and prosecution can still try to hammer out a plea deal in an attempt to avoid trial.
It is very important that people who are facing charges either show up for their arraignments or hire defense attorneys to appear for them. Missing an arraignment date will prompt the judge to issue a bench warrant for the defendant's arrest. Read more information on Nevada arraignments.