The letter 𐑘 makes the sound of the ordinary letter "y", as in "Yay! It works!" It looks like someone with their arm in the air because they're happy.

The letter 𐑢 makes the sound of the ordinary letter "w", as in "Woe is me!" It looks like someone with their arms hanging down sadly.

These two letters are an exception to the rule that turning a letter around changes it between voiced and unvoiced. They are both voiced.