Dependencies are those software based on other existing software. Nowadays it is a very common practice to reuse Open Source code of other projects, but it makes the task of compatibilizing licenses among them pretty difficult.
“Licensed helps GitHub engineers to make efficient use of Open Source software, as it alerts them of possible problems with the license of a dependency from the beginning of the development cycle”, explained GitHub announcement. Using this program, it is easier to choose which licenses are compatible with a development and can be checked throughout the developer’s work cycle.
To know all the details about Licensed, see the official announcement by GitHub.