Two sides to validate: 1) that your idea is something people will use and buy. The only way to figure this out is to go out there and talk to potential customers and users or try small tests to gauge their interests in your future product
2) That your idea can turn into a business: talk with advisors, other entrepreneurs and investors. The more you learn from successes and mistakes other people have made, this less mistakes you have to make yourself. Happy to chat on strategy here and discuss any of this further