Linux debian no boot loader installed

Definitely debian is not easy to install and this time i have this
Error " no boot loader installed" what is the boot loader and how can i install it ?
Help this is not an easy one. Should I continue the installation by forcing or clicking the ok button? i waiting to hear from you
The error image :
Continue without boot loader
No boot loader installed
No boot loader has been installed, either because you chose not to or because your specific architecture doesn't support a boot loader yet.
You will need to boot manually with the kernel on partition/dev/sda1 and root=/dev/sda1 passed as a kernel argument.
