Depending on how low the battery level is on your device (e.g., tablet, laptop), Windows 10 pops a few warning messages letting you know when the battery is low, critical, or running on reserves, and that you need to plug your device to a power source as soon as possible. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.