rank and file


It just takes a lot of practice. It becomes a lot easier when you play a lot of chess and think of the notation more often. chess.com also has a game called "vision trainer" that can help a little in a fun way too. On the chess.com left sidebar (Home, Play, Puzzles etc.) go to "Learn" and then "Vision." In the game, you can choose to name squares, moves or a mix of both; practice with both the White and Black perspectives (eventually, you can start with White, then Black and lastly alternate) and you'll improve at it.