Microsoft ships Windows 10 with Edge, the successor to its Internet Explorer browser (although IE is still present, Microsoft has recently announced that its days are numbered). For many people, however, using Chrome or Firefox is the norm, no matter what Microsoft wants.
To install Chrome or Firefox – and get back to normality – open Edge, search for either, and find a Windows 10 version. Download it, install it, and make sure it's set as the default browser option so that Edge doesn't keep reappearing.
To do this, head to Settings, System, and click on Default Apps – click under Web Browser and you can then select your preferred default browser.