WooCommerce Security??

"With WooCommerce, you’ll need to add most of the security methods to your online store yourself. This includes finding a reputable host with an SSL certificate and installing additional plugins to ensure your website is fully protected."

No clue what this means. I'm planning on starting a small business/portfolio, and don't understand the security measures. I don't want to go with shopify and have decided to use wordpress/woocommerce but yeah does anyone know anything