Thank you so much for playing, I will try to clear the doubt. So the thing with betting is if You bet 3 x circle, that means you believe that minimum 3 circles are there on the board (both your and npc's hands combined, which is 10 shapes at the beginning and goes down as game goes on).
If npc bets 4 squares let's say, that means no. Believes there are atleast 4 squares on board. If you don't believe so then you can call liar. Then the shapes are revealed and if npc's bet is true, means there are actually 4 squares on the board then you lose, if not then you win the round.
Hope that makes it clear. <3