BASLOAD is best described as a BASIC tokenizer. It takes BASIC source code stored on disk in plain text format, and loads it into RAM. While loading the file, it's tokenzied so that it can be run by the built-in BASIC interpreter.
The purpose of BASLOAD is to enhance the programming experience by letting you edit BASIC source code in the editor of your choosing without using line numbers. Instead of line numbers, named labels are defined as targets for GOTO and GOSUB statements.
Instructions on how to use it and source code is found here: