Every website on the platform gets a Free SSL certificate. The certificates allow you to have a secured connection between the customer's browser and the server. That helps in the prevention of hacking and stealing customer's information because the data is being encrypted from the customer's browser to the server.
All certificates are being installed automatically and you don't have to do anything. If your domain is connected correctly it might take up to 48 hours for SSLs to install onto a newly connected domain (In most cases it is within the day).