It's the right of the public to access private land. It basically reduces land ownership to the right to conduct activities such as forestry, agriculture, and fishing, giving everyone the right to roam that land as long as they don't cause problems for these activities.

I come from a country with the freedom to roam, and I consider it a fundamental right. I can accept limiting or discouraging access to areas in nature out of respect for endangered wildlife, but as far as I am concerned nobody on earth has the power to place a fence around a forest or field and claim nobody may enter it because it is "theirs". It's hard for me to understand that anyone accepts that bullshit.