Go here, insert the service tag number, open System Configuration to list all of the hardware installed.

Check if your system has dual internal hard drives. Some laptops ship with a relatively small but fast SSD intended for Windows and some applications, and ALSO have a large but slower spinning hard drive meant for large applications and media collections, for example. Windows always defaults to installing and storing data on the C drive though, so you won’t use the other drive unless you deliberately select to install applications there or store data there.

If you only have a single drive, then you could either replace it with a larger drive, possibly install a second drive internally (depending on the laptop model, which you didn’t specify), or yes add a USB 3.0 drive.