sublime-ledger-syntax is a Sublime/TextMate syntax definition file for Ledger (ledger-cli.org) files
The easiest way to install this package is through Package Control.
Otherwise, if you have Git: clone the repository in your Sublime Text "Packages" directory (Sublime Menu -> Preferences -> Browse Packages…).
If you don’t have Git, download the source zip and unpack it into a new directory named
sublime-ledger-syntax within your Packages directory.