Question about java encapsulation and this keyword

I come from a PHP background and I'm having trouble understanding encapsulation and more precisely this keyword, in theis example bellow:

public class Person {
  private String name; // private = restricted access

  // Getter
  public String getName() {
    return name;
  }

  // Setter
  public void setName(String newName) {
    this.name = newName;
  }
}

In the getter method why is name returned instead of this.name? afaik this.name refers to the Person object property, why name and not this.name?

Also in the example bellow:

public class Order implements IOrder {

public String uid;
private Map map;

public Order(){}
public Order(String uid){
this.uid=uid;
map = new HashMap();
}

Why is map refered as map instead of this.map, also why is there two(2) constructors instead of one?