Unfortunately, this is not quite an easy question to answer. You may install and activate the Windows Server 2016 standard normally. Then install the hyper-v role and install and activate 2 more Windows Server 2016 standard (Guest). However, you are not allowed to install another role on the host. Now comes the complicated part... You may install more than 2 windows server 2016 standard as guest with one licence. But that depends on how many CPUs and how many cores a cpu has that you install in a system. Threads do not matter. There is an overview here: https://www.software-express.de/wp-content...
This means: 1 system with 2 CPUs and 4 cores each (i.e. 8 cores in total) allows 4 guest systems with a 16 core licence.

There are also 24 core licences. However, this is the 16 core version. I hope this should make it clear.