I am beginner age 24 can I start workout and gym and...

Hello Mayank!
Yes, you can start working out at the Gym. You should focus on resistance training for your workouts. Regarding fat loss, you need to have a calorie deficient diet. In this context, it is always advisable to have a personal trainer for your workouts and to consult a nutritionist for a proper diet plan.

Yes, you can workout instead of gym you can start with basic like yoga and also balance your diet intake. The diet will help you lose weight, and exercise like yoga will tone your body. Sometimes it's challenging to control on our food n maintain your diet plan so try to train your brain by practising meditation and Pranayam.

For your first part of the question, the answer is yes. The gym is just a place or facility to achieve or fulfil your fitness goals which don't have anything to do with age in most of the cases.

When it comes to fat loss, slow, steady cardiovascular activities like cycling, running, swimming or any other activity which demands you to intake more air/oxygen and your legs are moving will lead you to fat loss because these activities utilise fat/lipids as the primary source of energy. When it comes to diet make sure that you are balancing out your calorific intake, eat less junk/unsaturated fats, feed more on fibrous food, whole grains, veggies, fruits, little bit dairy for proper fat intake.  It is only for fat loss, muscle building and strengthening is another topic to talk about. I hope this helps. Do let me know if anything more is required.

Ofcourse you can start now. The best way to loose fat is to intake less calories and burn more calories. Any form of exercises you can do. Like functional training, weight training, body weight training, resistance traning or you can always combine any of this for weight loss and muscle gain. All the best.