An Ubuntu Snap package, or just Snap is a distribution format similar to AppImage in that it is intended to be a "universal installable package" to deploy software in Linux systems. Snaps were introduced by Ubuntu but they are intended to run in all Linux distributions as long as the Snap daemon, or
snapd, is available in the target system.
The intention is that programs installed from a Snap are sandboxed so they do not interfere with the rest of your operating system, and moreover they can be updated automatically to get the latest features.
As of v0.19 the use of Snaps is experimental. The current Snaps are generated and hosted by volunteers.
To install the stable version of the Snap use:
sudo snap install freecad
To install the development version of the Snap use:
snap install --edge freecad-ppd
More information about current efforts to deal with Snaps.