Strength is a powerful card in the Tarot. It is a progression towards unification and development of feminine principles (versus previous masculine principles). The woman can be seen as the unconscious ready for new beginnings and initiatory magic. She is the mediator between the ego and the psyche. Her hands are fearless with the lion indicating a personal and human touch (thus the feminine principles) with a pure heart. Strength indicates a taming of our animal nature so we are no longer under its power.
Bearing this in mind, facing the lion requires strength for personal transformation. We must pay attention to the lion – it shows us that we need to hold onto our raging affects and accept it – becoming aware of our animal nature shows us that we can live with less personal rages and aspects we fear about ourselves. Be not afraid of this – taming the inner lion requires a mutual involvement and give-and-take. The lion is a natural beast, symbolizing self-fulfillment (their instinctual nature). It energizes the self, and it can be tamed and integrated. Strength and experience are needed to work with instinctual drives – otherwise, we can be overwhelmed. One needs the insight to tame the lion, and they can then move in harmony.
Source: Jung and Tarot: An Archetypal Journey, by Sallie Nichols