A horizontal line of squares is called a “rank”.

Each “file” and each “rank” has a name.

The names of the eight “files” are letters of the alphabet in order, starting from “a” on the left edge of the board, through to “h” on the right edge of the board.

shown on some chess boards by letters starting from the first “file” on the left, which is called the “a file”, all the way across to the eigth “file”, which called the “h file”.