This is an improvement or modernization of its components. Usually, the addition of a modern high-speed SSD is provided. And also, if possible, increase the RAM and replace the processor with a more powerful one. This is what determines the performance of the laptop. The Acer Aspire brand is good because in most cases it allows you to upgrade basic components. A laptop upgrade can also be in terms of peripheral devices (camera, microphone, Bluetooth, Wi-Fi, etc.).