The Fool is about choosing to move forward, about childlike wonder, and unabashed joy in living. New beginnings, new ventures, and wholesome fun. Sometimes this is seen as being foolhardy, or unwise, yet sometimes what seems too risky isn't so risky at all, or it's worth risk because The Fool is witty and clever.
If The Fool is in the obstacle position in a spread then it likely indicates that you actually are being foolhardy, and rejecting tried and true conventional wisdom, being too risky, or trying so hard not to act the fool, trying so hard to "be mature" that it hurts.
If The Fool is in the solution position in a spread then it likely indicates it's time for a leap of faith, but it's a fun one, and it's safe to make the leap. Remember childlike wonder, and fun, and go for taking the risk. Go for it, embark on the new thing. Wisdom is knowing when it's Time To Play and when it's time to Do The Thing.
NOTE: Using NO pictures is on purpose so that these meanings can be more easily applied to any Tarot deck using in the Smith-Waite system, aka: Rider-Waite Smith (RWS).