Your question would be better in the private flying section..
VFR stands for VISUAL FLIGHT RULES.
Which is basically when you fly you must adhere to certain conditions. Namely have the ground in sight at all times, remain clear of cloud and have visibilty of at least 10km, although this can be reduced depending on the airspace flown in. Most PPL's will fly under VMC ( Visual Meteorlogic Conditions ) unless they have taken an IMC ( Instrument Meteorlogical Conditions ) rating then they can fly in worse conditions but this is not be confused with an IR rating ( instrument rating )
Hope this helps.