The letter 𐑣 makes the sound of the ordinary letter "h", a breathing sound. Its name is "haha", which is the name of a kind of ditch in the ground, as well as the sound of laughing. It does go downwards like a ditch.

The letter 𐑙 makes the sound which we usually write as "ng". Even though it's usually written with two letters, it's one sound. Its name is "hung", which has the sound at the end instead of the beginning. This is because there are no words with "ng" at the beginning. It looks like a garland, hung up.

You often see 𐑙 next to 𐑦 at the end of words like "going" or "saying". Then it looks like 𐑦𐑙, and you can write it without taking your pen off the paper.

These two letters are an exception to the rule that turning a letter around changes it between voiced and unvoiced. But they are a pair in a different way: you can never replace one of them with the other and make a proper word. This is called "complementary distribution".