Counting is hard, even for humans. A child will start to speak at around the age of one, but most will be about two before they start to count. And it is even

Counting is hard, even for humans. A child will start to speak at around the age of one, but most will be about two before they start to count. And it is even longer (maybe the age of three to four) before they understand cardinality and can reliably follow “simple” instructions like “bring me four blocks”. And basic arithmetic without counting on their fingers is usually not picked up until they are around six or seven.