The legislation prohibiting foreign travel has been extended this week to cover the period up until 30 June. That doesn't necessarily mean that the travel ban won't be lifted before then. Neither does it mean that the ban can't be extended beyond that date. It simply means that the Government can now keep the ban in place up until 30 June without needing to seek any further Parliamentary approval.
So the reference that you've seen to 'from July' almost certainly means 'from 1st July'. Even if that actually becomes the date when travel to Germany is permitted though, it doesn't necessarily mean that quarantine restrictions for people returning from Germany will be lifted at that time. (So, for example, you might be able to travel to Germany but be required to self-isolate at home, or even in a hotel if Germany is on the 'red list' at that time, for 14 days upon your return).
It also doesn't take into account any restrictions that the German government might have in place. (e.g. you might be permitted to travel to Germany but only if you spend the first fortnight there under quarantine conditions),