I was wondering if there was any resources available online that explains what happens with something, like printf of C, that explains what\'s going on in the very low level
Something like printf, or printf specifically? That is somewhat vague.
printf outputs to the stdout FILE* stream; what that is associated with is system dependent and can moreover be redirected to any other stream device for which the OS provides a suitable device driver. I work in embedded systems, and most often stdout is by default directed to a UART for serial I/O - often that is the only stream I/O device supported, and cannot be redirected. In a GUI OS for console mode applications, the output is 'drawn' graphically in the system defined terminal font to a window, in Windows for example this may involve GDI or DirectDraw calls, which in turn access the video hardware's device driver. On a modern desktop OS, console character output does not involve the BIOS at all other than perhaps initial bootstrapping.
So in short, there typically is a huge amount of software between a printf() call and the hardware upon which it is output.