Sold a property 5 years ago. Do I pay taxes?

Hi there, my parents and I told our family farm 5 years ago to a family friend. The farm and land surrounding it was owned by my family for over 100 years and we decided to sell it in 2019. How doea capital gains work in this situation? We weren't sure when or if we need to pay taxes on it. Every year we've filed our taxes and haven't owed any money for it. I'm not sure what to expect.