Vocapic is a simple and free bilingual site that lets you learn either English, Spanish or French vocabulary.
First click on the top right to indicate the language you speak now, then move down to indicate the language you want to learn. You can then choose word categories where you are provided a word in audio and text and then asked to choose the correct response among three images. It works very well if you are a Spanish speaker and want to learn English.
There’s a section on the left of the home screen which indicates that if you click on it you will learn simple words. However, that doesn’t appear to work for learning English words.
I’m adding the site to The Best Multilingual & Bilingual Sites For Learning English.