You can block an specific IP addresses to access your website using .htaccess file.
You need to create this file in your public_html folder and add this line by mentioning your own IP Address.
order allow,deny deny from 192.168.10.5 allow from all
These method will now block the incoming traffic from that IP address, you can type your required IP address instead of this example IP.
You can download the list of each country IPs from following link: https://www.countryipblocks.net/country_selection.php