What if two Implementation of Interfaces are there?

Here is the link from previous video's teacher's notes.

There is a precise answer to your question: if you have two or more implementations of an autowired interface you can use @Qulifier("RightImplClassName") annotation. For example:

public Example {
  @Autowired
  @Qualifier("SomeInterfaceImpl2")
  private SomeInterface someInteface;
}

If you have two implementations, Spring will throw an exception, so you need to make sure you only have one. Check the teacher's notes in this previous video.

On a side note, you could have more than one implementation of an interface, but Spring will search for annotations on a class implementing that interface, so if only one class is annotated, you should still be ok and that's the class implementation which will be used for Autowiring.