* Musical Notes: In music, these letters represent the notes of the diatonic scale.
* Chess Board Coordinates: In chess, these letters represent the columns of the chessboard.
* Alphabet: They are the first eight letters of the English alphabet.
* Variables: In mathematics or programming, these letters could be used as variables to represent values.
* Acronyms: It could be the first letters of a phrase, forming an acronym.
To understand the meaning, you need more context.
For example, if you saw "a b c d e f g h" written on a chessboard, you'd know it refers to the columns. If you saw it in a music context, you'd know it refers to musical notes.
Please provide more information about where you saw "a b c d e f g h" so I can help you understand its meaning!