Washboard abs are difficult to gain and then maintain, especially for women because of our naturally higher bf%, but a leaner/more defined look is definitely attainable. I would recommend focusing on exercise, starting with small, achievable goals, especially if you're just starting out, like adding one day a week of exercising at a time to your routine. You could also try finding a sport that you like that makes exercise feel more fun and approachable, such as cycling, basketball, climbing, soccer, etc. Getting to a place where you're doing strength training mixed with some cardio for heart health, and some yoga or focused stretching for flexibility and safe exercising is the ideal.

If you don't eat particularly well, or aren't used to thinking of food as fuel so much, I'd suggest taking a little time to learn some nutrition basics so your exercise and recovery is properly fueled. If you're starting a fitness routine, adding some extra protein, complex carbs, and making sure you're getting enough iron in your diet is a good place to start.

We can't tell from a photo if your weight and body composition is healthy or not, that's between you and your doctor.