Okay, so think of your stomach like a cauldron where food goes in to get cooked. The acidity function is like the ingredient that makes it all work.
Just like how a chef measures out ingredients to make the perfect dish, your stomach uses acidity to break down the food you eat. This acidity comes from something called hydrochloric acid (HCl), which is produced in your stomach.
If you don't have enough acidity, your stomach won't be able to properly digest the food you eat, which can cause all sorts of problems like bloating and indigestion.
On the other hand, if you have too much acidity, it can also be bad for you. This can cause heartburn and damage the lining of your stomach over time.
So, your stomach needs just the right amount of acidity to work properly. To measure this, scientists created something called the acidity function. This is basically a way to rate how acidic or basic something is on a scale from 0 to 14.
If something has a lower number, that means it's more acidic. If it has a higher number, that means it's more basic.
In the case of your stomach, the acidity function measures how much HCl is in your stomach. So, if you have a balanced acidity function in your stomach, your food will get cooked up perfectly and you'll feel great.