A 504 Plan comes from Section 504 of the IDEA that provides legal documentation that strives for all students to be treated fairly. It is essentially accommodations for students who are in a general education classroom and does not have an IEP. There are no annual goals, no related services, no present level of performance, and no modifications. It is simply accommodations for students.
All of the accommodations need to be upheld by the teacher(s) themself(ves), not a special education teacher, therapist, or psychologist. There is also no parental approval needed, while it is helpful to have because students can be supported at home as well.
504 Plans should be reviewed annually to ensure that they are still meeting the student's needs. Every three years, students will be reevaluated to see if they still need a plan.