In context of a Windows setup, a hypervisor such as VirtualBox, VMware helps isolate your guest from the host (the main installation of your OS).
This is a considerate move in terms of Security, if you're dealing with activities or files/software that pose a risk to compromise your data. One example would be for Security Analysts, who is analyzing malware on a daily basis.
So, if this is your business computer: It might make sense to encapsulate an installation inside a virtual machine if you ever would lend your computer for someone to use it, download/install unsigned software or torrents, etc. Breaking out of a virtual machine takes some very sophisticated attacks, and is a highly regarded exploit on the 0-day market.
It's the guest you want to isolate from the host and not vice versa.
There is some operating systems such as Qubes (https://www.qubes-os.org/), who does app virtualization - which means that every single application run in it's own isolated instance.
Judging by your description of daily use you are a fairly low risk user.
Only open files, e-mails from trusted entities.
Have unique passwords, and change then regularly. Monitor leaks from hacked sites you might have registered yourself on through haveibeenpwned.com
Always use the latest version of your web browser, Adobe PDF, Java and Flash if you need them at all.
Be conservative with browser extensions.
Don't install unsigned, outdated or pirated software.
Enable 2-factor authentication for your crucial accounts such as GMail, Facebook, etc.
Encrypt your backups, if having any (pull).
Be considerate with how you choose to split up your virtual machines.
Configure your Virtual Machines with none or limited access to folders etc, on your host machine.
There is a myriad of software for hardening in Windows such as EMET (The Enhanced Mitigation Experience Toolkit), Microsoft Security Essentials and Windows Defender.
If you run a Linux based installation in your virtual machime, I'd suggest you to install a supported release and enable unattended Security upgrades, reboot the server whenever there is a new kernel installed.
These steps will improve the average users information security significantly.
NOTE: Don't forget that the virtual machine, separation only mitigates certain threats and attack vectors. There is a lot more to take into consideration to have all the Security best-practices in place.