The Lenovo X240 has an SSD storage medium which is better than the HDD storage medium found on most laptops of this spec and age. 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 in fact the best storage medium amongst all laptops that came out around the same time as the X240.
Amongst comparable types of laptop the worst storage medium is HDD.
If you are looking for a notebook PC with a better storage medium then you might also want to consider the Acer Aspire V3-371 (ssd), or the Lenovo Y70 (ssd) which is also cheaper.