While the exact requirements for a resume might vary by school, the general length is 1-2 pages and most every law school will expect one as part of your application. If you are a current U of A student, you can schedule a free one-on-one appointment with Student Engagement & Career Development to review your resume: https://career.arizona.edu/resources/how-to-make-appointment/. You can also use their Career Document Dropbox to upload your materials and receive free personalized feedback in 3-5 business days. Learn more here: https://career.arizona.edu/resources/career-document-dropbox/
Other resources to explore:
Application Toolkit: Resume – Harvard Law School Good overall advice
Converting Your Job Resume into Your Law School Resume in Five (Relatively) Easy Steps – University of Pennsylvania Thorough steps that can be helpful to follow