How often should I exercise?

Let's first acknowledge, that any exercise is a win. However, if you're looking to dedicate a few days a week to an exercise plan to maximize weight loss I would suggest a 1:1 approach for week 1 -> ONE day of cardio and ONE day of strength training.

Once you are ready to incorporate more, advance to a 2:1 -> TWO cardio and ONE strength training.

Ultimately you want to be working towards a goal of 2:2 -> TWO cardio and TWO strength training days.

Everyone is different in their journey so choose lengths and times that you can safely complete. Maybe it's more, maybe it's less. As a rule of thumb for starting out, 20 45min of cardio or strength training can yield results. I would never recommend going for more than 60min for either type of training. Use good judgment and listen to your body and take adequate rest.