How to resolve 'this connection is not private' error during checkout?

Hello,

I am having problem when somebody trying to check out they receive a message (this connection is not private)
how to fix this?

@Haialma

The “connection is not private” error can come from your store not having an SSL certificate applied and/or having additional DNS records that aren’t required. Could you provide your store URL so I can take a look?

Hiw do we fix this ?I have a domain from shopify???