Cambridge Dictionary: The Cambridge Dictionary is a great resource you can use to get English definitions to English words, along with the Spanish words, so that you learn English meanings using English definitions mapped to your native language. This gives you much clearer context on meaning in context than Google Translator, which often translates words incorrectly, especially in idiomatic expressions, which are translated more accurately by Cambridge.
SpanishDict: SpanishDict is an online Spanish/English dictionary that is so much more than just a dictionary. Of course, it performs all the functions of a normal language dictionary with translations of words from one language to the other. Additionally, it includes tools to help with verb conjugations, grammar, vocabulary, pronunciation, and there is even a thesaurus. SpanishDict offers a subscription-based “word of the day”. (Today’s word is el jacinto, which means hyacinth in English.)