What does really mean Single Responsibility

I am learning SOLID principles. I read a lot of things about the single responsibility principle but I don't get it exactly. I will give an example that what do I want to say.

Let's say we have an article service for managing articles. How should I design article service by single responsibility.

Is like that:

class ArticleService{

  create(){};  
  read(){};
  update(){};
  delete(){};

}

Or create a class for each operations like that :

class ArticleCreateService{

  create(){};

}

class ArticleReadService{

  read(){};

}

// and so on ...

According to single responsibility which is the best way to managing articles?

Thanks.