Probably the first challenge every language learner faces is vocabulary. Every day we encounter new words, and we need a method to keep track and practice. The traditional way to do this is to write down each word along with its definition. Maybe we do this on actual notecards, or maybe we use something like Quizlet. Whether physical or digital, the process is pretty much the same:
Find new word
Look up new word in dictionary
Write word and dictionary definition
Practice by quizzing ourselves
The problem is that this can be quite time consuming. This is particularly true at the beginning when when learners may be encountering new words every sentence.
I used to use a service called, lingua.ly. It had a Chrome plugin, and when you double clicked a word, it would give you a Google translation and add it to your word list. It wasn't perfect. Google translate was accurate maybe 90% percent of the time. If it wasn't correct, I would have to look up the correct definition and edit it in my word list. Still, it wasn't bad, but unfortunately their service has disappeared.
I have come up with two alternative options, and fortunately they both seem to be better than lingua.ly. The first is very close to the now dead lingua.ly. Readlang is also a free plugin for Chrome that will let you click on words you don't know, a translation is then provided and placed into your list of flashcards to practice later. The basic plugin is free. If you want to translate phrases instead of just single words, they offer a premium version.
The second option is to use wordreference.com. They provided an excellent dictionary, so when you look up words you get full definitions along with example sentences. Especially for intermediate and advanced learners, this is a key advantage. To create a vocabulary list, you'll need to create an account (it's free), and then you'll see an option in the left menu after you look up a word to save your history.
Click that View All link, and you'll have a running list of your words. The key advantage to this approach is the full dictionary definition as opposed to just a Google translate. On the negative side, it doesn't build flashcards, so you'll just have to test yourself from the list. Also, the vocabulary list is saved by device, not your login. So if you look up words on a phone and a computer, you'll have two different lists. Finally, they do have a Chrome plugin to simply look up words. By default, you have to type the word, though. If you want the convenience of simply double clicking (available in the options after you install the plugin), they charge, albeit a most $1.99.
Hope this helps. Good luck with your language learning.