What do HCL and pepsin do?

What is ' HCL ' ???

If you mean hydrochloric acid, then the formula is ' HCl '. It is a small/lower case 'l', NOT a capital 'L'.

Chlorine has the elemental symbol of ' Cl '. This is the international standard.

As you have given it 'H' is hydrogen, 'C' is carbon, and there is no element with the symbol ' L '.

They are found in the stomach and aid the second stage of digestion. The stomach operates at pH = 1, from the presence of 'HCl'.

NB The first stage of digestion is chewing in the mouth and mixing with saliva.