There are a couple of simple ways you can quickly verify which version of WordPress you are using. This is the very first step in the process to install the Trellis by Mediavine Framework, but it's also handy to check for compatibility with any plugins or extras you are thinking of installing.
Log into your WordPress admin. If you have the At a Glance widget installed, you can see the details of your version of WordPress there.
Log into your WordPress admin. Scroll all the way to the bottom of the dashboard page. You'll find the version in the bottom righthand corner.
Keeping WordPress up to date is important not just for new features and bug fixes, but also for security. Make sure you back up your site before updating just to be on the safe side.