Can Juju be used on a single server to make it easier to deploy services like MySQL and any other Charms that are available? I understand that it is a tool to deploy and manage huge cloud servers but can it just as well be used on a single server to utilize the simplicity of charms?
You can use Juju together with the default multiple-server-install coordinator (called MAAS) to deploy charms onto physical machines, or extra physical units to existing services. Juju with MAAS lets you treat a group of physical machines as a cloud, essentially.
You can also run charms directly on your workstation, which we call a local environment. You run each separate service unit as different LXC container on a single machine.
See https://juju.ubuntu.com/docs/provider-configuration-local.html for documentation on configuring a local provider.