Cura is a slicing software that sets the options for a 3d printer to follow and then creates detailed instructions for the printer by creating a g-code file. This file can be saved to an SD card and transferred to the printer.
Note that Cura is not software that can be used to design a model, it is basically a program that takes a final design and translates it into the printer's language.
Cura is open source software, anyone can download and install it for free on their personal computer.
Install Link: https://ultimaker.com/en/products/software.
For more information on Cura, please see the online instruction manual.