The HP Pavilion x360 13-s052sa has an SSD storage medium which is better than the HDD storage medium found on most laptops of a similar age and type to it. Solid State Drives (SSD) store data in semiconductors on a circuit board rather than using magnetic or optical media. Solid State Drives have no moving parts which makes them very fast and reliable.
An SSD storage medium is actually the best storage medium across all medium processor core notebook PCs that have been around for a comparable time to the Pavilion x360 13-s052sa.
An HDD storage medium is the worst storage medium across similar types of laptop.
If you would prefer a portable PC with a better storage medium then you might want to consider the T420s (£1,388.87) (SSD), or the X1 Carbon (SSD) both from Lenovo.