This isn’t a card about physical strength. That girl on the card is not going to be bench pressing anything impressive. The Strength of this card is an internal strength – courage, fortitude, and patience. This is the card of the indomitable spirit. The wolf could easily kill and devour the girl, but it does not. Why? Because she has tamed it. How? By standing firm in the face of danger, by understanding that her will is stronger than that of the beast, and by having confidence that even small amounts of force can have an effect if applied persistently over long periods of time. If she had stopped at any point, or tried to force the wolf under her control, she would have failed and been eaten – instead she stands firm and waits, and eventually conquers it.
(Though in Ravenloft, it could just mean she’s a werewolf. Let’s just ignore that interpretation for now, shall we?)
Much like Victory, the beast on this card can be taken to represent one’s internal emotions and desires (though it can also be taken as an external force). The lesson to be taken from this is that you cannot make the beast obey you by engaging it on its own terms – you’re just going to get tired out, and the beast is a lot stronger and nastier than you are. Instead you have patience, don’t back down, and wait for it to tire. Eventually, the beast submits without any physical struggle at all. You can compare this card to staring down a large and dangerous predator – if you attack it, it would fight back, and you would probably lose, but by imposing your will over it, you can make it back down without a fight.
(Don’t take this as actual wilderness advice, however. Especially not against things like moose.)
This card can also indicate a form of harmony, either internal or with nature.
Remember how I said you can’t make the beast obey you, by struggling with it? This is you, trying to do that. Now you’re tired out, the beast is angry with you, and if you back down so much as an inch you are going to be eaten. Strength inverted is a warning, more than anything. First of all, you cannot achieve your goals through force or domineering. Second of all, you’ve expended far too much force on methods that aren’t conducive to your goals. Third of all, don’t give up or back away, or things are going to go pretty badly. You’re going to need to gain the self-confidence and courage to keep your ground in a bad situation, while recognizing that you can’t jump the gun and try to struggle your way into a quick victory.
Also, I’d look out for wolves.