Hi, and welcome!
Sometimes when you download an app, it tries to be helpful and creates a shortcut while it is installing.
If you want the icon, but do not want it on the first page, press it till it wiggles, then move you finger (with the icon still under it) to the edge of the screen until the page turns to the screen where you do want it.
If you do not want the icon at all, press it till it wiggles, then look for the little trash can that pops up at the top or bottom of the screen, then just drag the icon to the trash.
If you did not download anything and apps are installing themselves on your device, you have a problem--download an antivirus and do a scan to see if you can find the problem.