The Devil is one of those cards that, when they come up in a reading, may instantly scare you a little bit. Like the Death card though, the Devil doesn't have such an ominous meaning as may easily be inferred from just looking at the horned god Baphomet on the card.
Receiving this card in a reading means that perhaps you have been doing shadow work (or should be doing so!) or are coping with the effects of addiction or codependency in your life. Everyone has darker tendencies within themselves, and it is important to face them and bring balance back into your life.
When you do shadow work, you look at aspects of yourself that you may not like very much, and integrate these aspects into yourself though forgiveness and working on limiting beliefs. The Devil card signifies that it is time to do this inner work that we often fear.
If you are struggling with addictions, the Devil can indicate that it is time to get into recovery. You can attend a group like Alcoholics Anonymous, or go to a therapist to work on your addictions individually. Similarly, if you are struggling with codependency in relationships, therapy can help.
Another possible meaning to the Devil card is overindulgence in pleasure, including sexual pleasures. You may have just found a new love interest, and if this is the case, it is important to remember to set boundaries and not loose yourself to codependency. It is easy to do in the honeymoon phase of a relationship, but remember, you don't want to have blinders on and ignore red flags.
Many of us have a tendency to overindulge in food as well, and if this is you, the Devil card may be a warning to be more conscious of your apetite, and practice healthier eating habits.
Whichever meaning fits with your situation, the Devil card heeds you to take caution not to overindulge. Keeping balance in your life is important, and it is important to balance the desire for an instant dopamine hit with your longer term goals and desires. Pleasure isn't a bad thing, but too much can throw your life out of balance in the long term.