The phrase "summer days" refers to the period of time during the summer season. Summer is one of the four seasons, and it usually lasts from June until August in the Northern Hemisphere or December until February in the Southern Hemisphere. During this time, the weather tends to be warm and sunny, with longer daylight hours. The phrase "summer days" can also refer to a carefree and relaxed time of year when people often take vacations, spend time outdoors, and enjoy various activities such as swimming or barbecuing.