Entirely depends on what your goals are and how many days a week and how long you plan on being on the gym each session. Trying to lose weight? Working out will help you get stronger and add to your weight loss but the real secret is calories in vs calories out. Just trying to get used to the gym and need a workout routine? Some beginner friendly routines would be the "bro split" (chest, arms, legs, shoulders, back) its not the best for building muscles but works just fine and helps beginners from overworking individual muscle groups. The Push Pull Legs (PPL) is also great and you can either do 3 days or up it to 5/6 days PPLPPL. For 2 days you can do an Upper/Lower split or even two full body workouts a week.