Your dream is rich with symbolism and seems to reflect various aspects of your life, relationships, and personal experiences. Let's break it down.

1. Walking with Others: The presence of 2-3 people suggests a social aspect of your life. It may represent your connections with others and your comfort in a group setting. The wet streets could symbolize emotions or experiences that are currently influencing your journey.
2. The Young Girl: The girl resembling your sister might indicate a sense of nostalgia or a connection to your childhood. Her request for a ride home could symbolize a need for support or reassurance, reflecting your protective instincts toward loved ones.
3. Inside the Building: The transition from outside to inside could represent a shift in your focus or a desire to explore new opportunities (the different types of bread). The setting might signify your exploration of personal growth or an interest in nurturing aspects of your life.
4. The Swimming Pool: Swimming is often associated with emotions and navigating through them. The structured, therapeutic nature of the swimming suggests a desire for control and support in managing your feelings. Being assigned to watch someone swim correctly may indicate your role in guiding or supporting others, reflecting your nurturing side.
5. The Rubber Bathing Cap: This could symbolize protection and a sense of preparedness. It may also suggest that you feel the need to conform to certain expectations or roles in your life.
6. Compliment and Guidance: The compliment about your swimming guidance could point to recognition of your abilities to support and help others in your waking life. It may hint at a potential career path or a calling to assist others in their personal journeys.
7. Your Past Swimming Lessons: The connection to your past experiences with swimming lessons and your sister passing the test might indicate unresolved feelings about competition, achievement, and familial relationships.

Overall, your dream suggests a journey of self-discovery and the importance of relationships in your life. It encourages you to explore your emotional depths, consider how you support others, and reflect on your past experiences to guide your future. You may want to think about how you can express your nurturing qualities in your waking life and perhaps explore opportunities where you can guide or assist others.