When you learn the game of bridge the emphasis is on bidding suits you genuinely hold. This will tell partner (beloved partner) useful, constructive information about your hand so they may then make (you hope!) the correct decisions.
As you slowly progress you will begin to realise that some bids have been set aside for other specific purposes. They do not actually mean what they appear to say. These bids are known as "Conventional" bids.
One of the most useful of these bids is the opening bid of 2 Clubs. It says nothing about the Club suit itself at all: either its quality or its length. The meaning assigned to it is that you have a hand that is super massively powerful.
If you add together all the values in the pack for Aces, Kings, Queens and Jacks you will find the total is exactly 40 points. Experience has shown that - most of the time - if your partnership has a combined total of 25 points, then some kind of Game contract should make. It follows, therefore, that if you hold yourself, in your own hand, more than half of those possible points - 20+ - then you are in an incredibly strong position. Partner needs very little for you as a pair to be bidding Game. But how do we inform partner of our collective great good fortune? Across the world in nearly all systems it has been decreed the bid assigned to impart this delicious information is 2 Clubs. This is the "Standard" bid that says: "I am super massive - keep bidding!" This forces partner to bid even if they hold less than the normal 6 points required to respond to an opening bid. They MUST bid!
The general requirements are that a balanced, No Trump kind of hand should hold at least 23 of those wonderful points. This hand should open 2C!
But not all powerful hands are so flat. There are other more distributional hands that even though they have fewer points, are just as strong. These hands need a minimum of about 20 points:
Partner will need only have any of the Kings (3 points) for game to make on most layouts. If you open 1S you will most probably miss that game. So force partner to bid - open 2C!
You need to be in game whenever possible because of the bonus. In all forms of the game - Rubber, Teams or Duplicate - those bonuses are what it's all about. Bid those games.