As a writer, Dictionary is one of my favorite apps under macOS. It’s also one of the most underestimated.
It includes English, French, German dictionaries, and a few others. It comes with an integrated French-English dictionary, and others I don’t use. You can use it as a front-end to search Wikipedia. Add to that a tight integration to macOS—you can invoke it from almost any app containing text, with a gesture or a right-click on a word—it’s hard not to love this app.
The Mac Dictionary, with a partial list of dictionaries.
If you’re looking for little/simple/easy to use screencast recording app, without all the bells & whistles but all the essential stuff, have a look on Screenbits Screen Recorder—it’s on sale on the Microsoft Store at 7,99 instead of 19.99.