For your first Brazilian Jiu-Jitsu class, you only need a few simple things.
Bring comfortable athletic clothing, a water bottle, and a positive mindset. If you are attending a gi class and do not yet own a gi, regular workout clothes are fine for your first visit, and the staff can guide you on next steps afterward. For no gi classes, athletic shorts without pockets or zippers and a fitted t shirt or rash guard work well.
Personal hygiene is important in close contact training, so arrive clean with trimmed nails and minimal jewelry. Showing up a few minutes early is also helpful so you can meet the instructor, ask questions, and get settled.
Most importantly, bring an open mind and a willingness to learn. Everything else will be explained once you arrive.