if hcl is present in our stomach then why not the lining of our stomach doesn’t burn
It’s because the mucous cells secrete slimy alkaline mucus. The acids can’t eat through the mucus, so the walls of your stomach are safe!
Bicarbonate(HCO3-) is alkaline, a base, and neutralizes the acid secreted by the parietal cells, producing water in the process. This continuous supply of bicarbonate is the main way that your stomach protects itself from autodigestion (the stomach digesting itself) and the overall acidic environment.