"Remember that map passes the array index as a second argument to the mapping function, which are used here to know the x- and y-coordinates of a given character."
Since which refers to the array index, which is singular, the verb should be singular too.
Perhaps something like this?
"Remember that map passes the array index as a second argument to the mapping function, and the array indexes tell us the x- and y-coordinates of a given character."
"Remember that map passes the array index as a second argument to the mapping function, which are used here to know the x- and y-coordinates of a given character."
Since which refers to the array index, which is singular, the verb should be singular too.
Perhaps something like this?
"Remember that map passes the array index as a second argument to the mapping function, and the array indexes tell us the x- and y-coordinates of a given character."
Thanks