"learning WordPress" is pretty vague. What do you want to be able to do? Develop/code WordPress themes, plugins, etc...? Throw something together without knowing how to code? Just use it as a way to post blogs for your business?
You could learn any of the above without needing to pay for anything, simply by searching for tutorials & guides on YouTube or by Googling something like "how to build a WordPress website". The only things you'll likely need to pay for are your domain name and hosting for your website.
Note: use wordpress.org and host WordPress on your own server, instead of using wordpress.com which is merely a very locked down hosted version of WordPress that limits what you're able to do without paying for more expensive plans.