Q:

What does holding a resource is a class invariante mean in RAII?

What does mean holding a resource is a class invariante in RAII?
On the RAII's Wikipedia page it does states:

In RAII, holding a resource is a class invariant, and is tied to object lifetime: resource allocation (acquisition) is done during object creation (specifically initialization), by the constructor, while resource deallocation (release) is done during object destruction (specifically finalization), by the destructor. 

On a D language example, we can easily understand what does a Class Invariant means:
class Date {
  int day;
  int hour;

  invariant() {
    assert(1 <= day && day <= 31);
    assert(0 <= hour && hour < 24);
  }
}

It is a constraint referring to what can class field to hold on to be considered on a valid state. However what does it has to mean with holding a resource? Does it mean the resource is mine and will be mine from its construction by the constructor, until its destruction by de destrutor?

A:

Does it mean the resource is mine and will be mine from its construction by the constructor, until its destruction by de destrutor

In a correctly design program this is the case but the concept of ownership is not enforced in C++. 
It is easy to "shoot yourself in the foot" and give the resource to some other object. For example, when the resource is a pointer, you can accidentally share it between objects, like this:
struct A
{
    int some_variable;
};

struct A_holder
{
    A* ptr;
    A_holder()
    {
        ptr = new A();
    }
    ~A_holder()
    {
        delete ptr;
    }
};

int main()
{

    {
        A_holder a_holder;
        auto another_A_holder = a_holder;
    }
   //error because delete is called twice:
   //first on A_holder's pointer and a second time on another_A_holder's pointer
    return 0;
}

See https://rmf.io/cxx11/rule-of-zero for the rule of zero

