Maven is an open source built tool that can be used in the workflow of working on Java projects to manage dependencies and the build process. There are other similar build tools available such as gradle, ant, make, etc. Build tools become very useful with larger code projects.
Information about installation and running maven can be found at the project homepage https://maven.apache.org/
Maven requires a pom.xml file at the root directory of the project structure. It works like a recipe in specifying the dependencies required for the project (i.e. borrowed open source libraries) and also specifying the way the project should be built.
The syntax for running maven is
mvn [options] [<goal(s)>] [<phase(s)>]
The options and phases can be referenced by typing in man mvn in the command line to access the manual.