In English we distinguish between count nouns and non-count or mass nouns. Consider what feels wrong about these sentences:
- My glass is full of waters.
- I’ve got sands in my shoes.
- Could I borrow a money?
- I want to buy a furniture.
The reason these are wrong is that water, sand, money and furniture are examples of mass nouns. They are STUFF. You cannot pluralize stuff and you cannot refer to “a stuff”.
Why am I telling you this? Because “code”, as in lines of computer code, is also a mass noun. Code is STUFF. You cannot refer to “codes” and you cannot write “a code”.
Please try to remember this!