Hello, i have struggled to understand what does the lamda mean in the production function? please explain

Y=K\"z*(N)""*. where Z is land, which we take as a fixed factor which, contrary to capital, cannot be produced. Dividing by N we get production per capita: We)... where it > 0. Now, production per capita depends not only on the capital stock but also on the amount of land per capita. A country with little land per capita will be poorer and a country with much land will be richer. in practice, however, agriculture constitutes a small share of the economy in rich countries. As we saw in Chapter 1, production in agriculture constitutes only 13 percent of GDP in the richest countries. Also, differences in population