Don't get frustrated. Please read java tutorials first and understand the concepts. your exam question is very clear on what you need to do. Atleast for this question, you need to know what is constructor, the purpose of having toString() in a class.
May be the below can help you.
public class Element {
private String elementName;
public Element(String elementName) {
this.elementName = elementName;
}
@Override
public String toString() {
return elementName;
}
}