What is the formula for kinetic energy?
Temperature is a measure of the kinetic energy.
This means that if we say that the temperature is high, we actually mean that the average kinetic energy of the molecule is high.
This is important in chemistry as kinetics influences chemical reactions. If a particle has a high kinetic energy (has a high velocity) then it has a higher chance to react with some other particle, causing a reaction. This can be visualised in a potential energy diagram.