"Lychee" stands for the lychee fruit. In this context, it is probably the rough shell of the fruit. If so, the grain of the material should resemble the fruit surface but it is probably a piece of Embossed leather.
Lychee-PU has a surface like the lychee fruit.
"PU" is presumed to be polyurethanes. A plastic, which is often used in the coating of leather, is also used in artificial leather. PU leather is also another type of leather. It is therefore to be assumed that the surface coating consists of polyurethanes.
The appended word "leather" indicates the tanned skin of animals. But it is not exactly clear if this material description is really leather as per the definition. There are no known studies on this. The bad experiences in examining leather belts and mobile phone cases warn us not to rely solely on the trade description.