They invest the majority of their profit after operating costs to tree-planting globally. One of their partner agencies is Ondernemers Zonder Grenzen, a Belgian group working in Burkina Faso, one of the countries in the Green Wall project. Here is an example of how much can happen in one year from one of OZG's planting sites in Burkina Faso: http://www.ozg.be/single-post/2017/09/14/We-keep-our-promises-Testimony

If you want to help the world by planting trees, I recommend you look at Ecosia as an alternative to the corporate search engines. They publish monthly financial reports showing where the income and expenses are going and as of a little later today will have funded the planting of over 14 million trees globally. https://info.ecosia.org/what