Rate of heat transfer between two objects
Heat will flow between one object and another if the two objects are at different temperatures. Temperature is just a measure of how much thermal energy (sometimes called 'internal energy') an object contains.
So the greater the temperature difference between an object and its surroundings (air for example), the greater the rate at which heat energy is transferred. This means that if you have two objects with a large temperature difference, then a large amount of heat energy will flow from the hotter to the cooler.
Note that heat energy CANNOT flow from a cooler object to a hotter object naturally.
The important idea here is to identify the temperature difference between an object and its surroundings (or another object). The larger this difference is, then the larger the rate of heat transfer will be, assuming that heat is allowed to transfer via conduction, convection or radiation.
GCSE Physics Keywords: Rate of heat transfer, Temperature difference, Heat energy