Which distro are you using?
Are you running a GUI interface?
What kind of VM do you want to run?
Gnome Boxes?
VirtualBox?
Docker?
Podman?
Libvirt?
How much total RAM do you have?
You will have to subtract whatever you give the VMs from this.
How many CPU cores do you have? Does your
system support hyper-threading? (Most modern day systems
have two threads per core).
You will have to subtract whatever you give the VMs from this.
How much hard drive space do you have?
You will have to give some of this space to the VMs.
Are you planning on running a full VM? With a full operating system,
or are you planning on running an application container like
docker, vagrant or podman?
How many network interfaces does your system have?
Are you planning on using NAT, bridging, or something else?