WordHolic is the best and simple and free and easy-to-use flashcard maker for all kinds of learning languages and tests.

The free version is great for learning languages, but there are a few limitations: It is a free app, but it has ads on the screen. Ads can be removed for a small fee. The payment for removing ads will be charged to your Google account. 

You can also create sub-folders to organize your flashcards by topic and import files from your computer. If you want, you can share the flashcards you made with your friends, helping them review for an upcoming test or graded recitation.