So, you know how when you do things, like coloring or playing with toys, sometimes you want to remember what you did? Well, people who are Buddhists sometimes do things that are important to them, like praying or meditating. They want to remember what they did so they can do it again and also so they can share with others what they learned.
Now, imagine you're at a beach and you're having so much fun playing in the water and building sandcastles. But you know that soon you'll have to go home and you won't be at the beach anymore. So, what do you do? You take some sand and put it in a bottle. That way, when you get home, you can open the bottle and remember the fun you had at the beach.
Well, some Buddhists who were traveling to different places did the same thing, but instead of sand, they wrote down everything they did and learned in a special book. They wrote their prayers, their thoughts, and their teachings, so they won't forget them.
And when they were at the southern sea, which is a big body of water with beaches and waves, they wrote everything down in a book and sent it home to their friends and families. This book is special because it has all their memories and important teachings that they want to share with others.
So, a record of Buddhist practices sent home from the southern sea is like a really cool book that has important things that Buddhists did and learned while they were at the beach, and they sent it to their loved ones so they could read about it too.