Some updates do increase the size of the Windows 10 installation, but aside from that, when one downloads an update that can be anywhere from 1 to 12 GB in size, it can put the squeeze on hard drives which are already feeling the pressure. Remember that while the program is installing, it needs a significant chunk of HDD space in which to use as a swap. @Random_Spock is likely worried that one of these installs or updates will hit the hard limit on his HDD.
Exactly. Not a lot of real estate. I'll be backing up to my external hard drive, and moving what I can to Photobucket, but space will probably still be somewhat of an issue.