The phrase "to a lesser extent" means that something is happening or being done to a smaller degree than another thing. It can be used in various contexts, such as describing how two events are related (e.g., "the storm caused damage to cars, to a lesser extent, buildings"), comparing the intensity of two things ("she was sad, to a lesser extent, happy") or explaining why something is not as significant as another thing ("his contribution to the project was important, but to a lesser extent than others").