Is there a free cloud service where I can practice installing Linux?
You can do it on your own current operating system.
Use Virtual machines (Virtual Box is good) and install any number of machines(which are called guests). Try them, test them out without harming the stability of your main system(which is the host).
Most virtualization software is available for Linux as well as Windows hosts.
Hope that's a better solution than a cloud service. Most people use virtualization to accomplish testing and trying.
Google Cloud Platform Free Tier:
The Google Cloud Platform Free Tier is your opportunity to learn and use GCP for free. It has two parts: a 12-month, $300 credit free trial and Always Free. The 12-month, $300 free trial allows you to use any GCP product. Always Free allows you to try participating products for free up to their non-expiring usage limits, making it easy for you to test and develop with these products.
Basically you get a 300 dollar credit and that credit does not end so you have a free cloud setup. For a test and trial more than enough.
2 small issues:
- you must have a valid credit card to register
- it is easy to "up" the cloud instance and getting charged (though they do warn you extensively if you do).
But they do have the latest Ubuntu LTS and all the normal versions after that LTS (Plus Debian and Gentoo).
I do agree with Yaksha: you can do this on your own system using virtualbox or vmplayer. Google cloud though has the benefit of you learning Google cloud. Something that you might benefit from in the long run.
For this, you can use virtualisation. I use VirtualBox for this.
To keep explanation very simple for the beginning, you just run a virtual computer "in a window". Changes to this won't affect your main operating system, you can restore older states, and run different os at the same time.
As networking is also very important for learning, you can create virtual networks between your virtual systems, but I would start with one system.
Just install ubuntu from an iso, and you can begin!