You can speak on the weather, the activities you done such as BBQ, hiking, biking, parties etc. This is a common question you should be able to articulate in your own way.
Dear mom and dad this weekend at my friends house has been amazing. We did lots of cool stuff and I learn a couple of things about my friend’s family. I learned new things that we could try out. My friends parents were very nice to me and asked if I could stay some other time