A minor is a package of course subjects of (in most cases) in total 15 ECTS. A minor offers you the opportunity to specialize yourself, or broaden your knowledge and competences. A minor can be taken of your own educational programme, but also from another programme or even faculty. There are a lot more options. More about these other options can be found here.
In Module 7 you can choose between 2 modules, namely M7A: Device Physics or M7B: Network Systems. For additonal information see the links below.