NUMA stands for Non-Uniform Memory Access. It is a memory architecture in which each processor core has its own local memory but other cores have permissions to access it.
Paraller GC, when used with -XX:+UseParallelGC is NUMA Aware for couple of years. It improves the performance of configurations running a single JVM across multiple sockets. With Java 14, G1 is enhanced to manage memory usage better.
The Z Garbage Collector is a scalable, low-latency garbage collector. It was first introduced in Java 11 as an experimental feature. It supported only Linux/x64. With Java 14, now ZGC is ported for Windows and Mac OS as well. At present too, it is an experimental feature. From Java 15 on wards, it will become a part of standard JDK release.