Money is what we use to buy the things we need. It comes as coins (of different values) and bills (of different denominations). Each coin or bill has a value printed on it.
When we want to buy something, we need to know its price, then add up the money we have to check it's enough. Example: if juice costs 2 dinars, and we have one 1-dinar coin and two half-dinar coins, our total is 1 + 0.5 + 0.5 = exactly 2 dinars.
It's also important to understand “change”: if we pay 5 dinars for something that costs 3 dinars, we get 2 dinars back as change. Practicing counting money helps children understand the value of money from an early age.