it means that instead of a spinning physical hard drive that there are chips that save data to the computer. it acts a little bit like ram memory modules, the difference being that ram is much faster than flash drives but ram doesn't save anything once you shut the computer off.

the advantage of flash memory is that it's much, much faster than traditional spinning hard drives. you notice the difference immediately. the disadvantages are that it's more expensive and the storage limits are smaller due to cost. a laptop hard drive costs $50 for 500gb. a flash drive costs about $150-250 for a 128gb drive.