IFR stands for International Financial Reporting.

During IFR flight, ATC will dictate cruising altitude.

Issued For Review

Any pilot (PIC) wishing to operate under IFR at Sion shall be trained and qualified for the local IFR Procedures with an aircraft able to operate on the IGS Steep Approach (initial 6 degree glide path

VFR or Visual Flight Rules means you generally have good visibility and are in a certain range of altitudes. You basically fly using what you see (and of course navaids and charts).

IFR or Instrument Flight Rules are used at certain altitudes, with certain types of aircraft and under certain kinds of visibility. Under IFR, you fly by using navaids, charts and instruments. Oftentimes you'll have zero visibility but IFR lets you fly in these assuming you're IFR certified.