Recently I discovered a new extension called Toucan that helps you learn a new language while you browse the web. Once you install Toucan, you will go through their onboarding experience that will ask you what language you want to learn and it will teach you how the extension works. Now when you visit any website, it will replace certain words with the language you are trying to learn. Words that have been converted by Toucan will be highlighted to make them stand out. You can also hover over them to see the word in your native language. Wikipedia articles are a great way to test out Toucan.
Toucan currently supports Chrome but the team is working on a Firefox and Safari version. Toucan will teach you Spanish, French, German, Italian, Portuguese, Korean, Japanese, and more languages coming soon! Personally, I have always wanted to learn Spanish. What language would you like to learn?