Boyle's Law is a relationship between pressure and volume at a constant temperature.
#P_1V_1 = P_2V_2#
In this relationship, pressure and volume have an inverse relationship when temperature is held constant.
If there is a decrease in the volume there is less space for molecules to move and therefore they collide more often, increasing the pressure. If there is an increase in the volume the molecules have more space to move, collisions happen less often and the pressure is decreased.
vV ^P ^V vP the relationship is inverse.
If temperature is changes then the gas law involved would be the combined gas law which incorporates all three values and the temperature and volume would both have an effect on the pressure.