There are 3 distinct types of bids where you start with 2. All of them show strength. The first we are going to talk about in this lesson is 2 No Trump.
One No Trump was a weakish bid with 12-14 points. Two No Trump is very different. You have between 20-22 points, and should have a flat hand and all suits covered. If you have a long suit, you might well be better to be bidding in 2 of a suit rather than 2 No Trump, but we will talk about the requirements for that in the next lesson.
A 2 No Trump opening bid is not a forcing bid - but your partner is expected to respond positively with a relatively weak hand - knowing that you have 20-22, they should respond with 4. If they have a long suit they should bid it, and if not, they should reply 3 No Trump.
Here is North's hand on which he opened 2 No Trump.
East will No Bid. And here is South's hand.
43. What is South's best response bid?
a. No Bid
b. 3 Clubs
c. 3 No Trumps