Definition of Value
Human always follows and find Happiness. Although it's very difficult to find, everybody has different happiness. Some people think money is happiness or a happy family, others think happiness is the peace of the soul (like a monk)... So we can say "what makes people happy is value for them".
The company is the same. Of course, every company has an ultimate purpose is revenue (except you are running a non-profit company). So, values of them are making the customer happy, good culture, good processes. over that values is assumed to have more money or save more money.
As a Product Owner, what are your product values?
As Product Owner, you must bring the benefit to your organization by earning money. Because that's a reason we have the business. The other side, you also need to make your customer or end user happy. And the happiness of customer link to your product values.
Both of sides are connected by you, Product Owner. So you need to understand your business and your customer. You can't find money without a customer who happy to use your product.
"Customer come first and money is follow after"
How do you know that's a value?
I got the same question likes this from many people, "How do you know that's a value?" I always answer: release and analyze it.
Software development is complex (cause of Technology, People and Market). So, to identify customer happiness, you need to release assumption values to market soon and frequently. Your assumption about values can be failed, it's good - make it fails fast then we can learn, and each of fail will bring us closer to the real value we need to deliver (except you don't learn anything from the last fail). Do you remember Thomas Edition tried how many times before he found the right material to invent the light bulb?
Treat your client as well as they are king, bring to them the right value they need at the right time. The Value Proposition Canvas will help you easy to imagine and manage. Combined it with your Lean Canvas is will bring more power to the tools.