Safe Mode and the BIOS are two completely different things.
If you have an older computer that still uses the BIOS to boot, you can get to the BIOS screens by restarting your computer and then, while the computer is starting, tapping the function key specified by your computer manufacturer. It might be F2 or F12 or the Delete key ... or something else. The computer manufacturer can tell you which key to press.
If you want to get to Safe Mode, but you're not able to do that from within Windows, use any of Methods 4 to 7 described in 7 Ways to Boot Into Safe Mode.