See
here for ways to check if you've got Secure Boot enabled.
Personally I don't see the point of Secure Boot in non business environments. The idea of Secure Boot is to prevent a hacker from booting an unrecognized OS/boot loader on your PC or adding custom UEFI boot drivers to your system. Well, for the first issue that hacker must have hands on access to your PC and there's nothing stopping that hacker from booting Windows or Linux from USB since those OSes are of course on the list of approved, safe operating systems. And if someone was able to secretly add malafide UEFI boot drivers on your PC, then you were already hacked.
Secure Boot makes sense in business or government environments where they handle top secret documents. You don't want a hacker to insert a USB drive into a PC, hack the UEFI BIOS and then have the PC run hacking code before the OS has even loaded. There it makes a lot of sense.
The downside of SecureBoot is that the list of approved operating systems is small and it's very, very hard to get on that list. At work I use iPXE as a way to boot multiple OSes from either the HD or the network in examination class rooms. The PC boots from the network, loads the iPXE file and shows a menu. Works great - but only with Secure Boot turned off since the iPXE boot loader is not on the approved list.