<..> when declaring a class

Hello guys,
I have one question. What does it mean when you put <..> in the class declaration line? Here is one example, KeyType is in there:
when calling registerEvent method, the input to a KeyType place goes a String. How come? Can anyone explain?

Code java:

public class InternalEventManager<KeyType> {
 
    HashMap<KeyType, ArrayList<WeakReference<InternalEventListener>>> eventMap = new HashMap<KeyType, ArrayList<WeakReference<InternalEventListener>>>();
 
    public void registerEvent(KeyType type, InternalEventListener event) {
        if (!eventMap.containsKey(type)) {
            eventMap.put(type, new ArrayList<WeakReference<InternalEventListener>>());
        }
 
        ArrayList<WeakReference<InternalEventListener>> list = eventMap.get(type);
 
        WeakReference<InternalEventListener> reference = new WeakReference<InternalEventListener>(event);
 
        if (!contains(type, event)) {
            list.add(reference);
        }
    }