Web traffic goes through numerous hops between the visitor and the web server, and so traffic each way can be read at any point on the journey if unencrypted. An SSL certificate enables encryption between these two endpoints, thus preventing "man-in-the-middle" attacks.
An SSL certificate is only good (trustworthy) if the private key is not compromised. That's really all you should be worried about, and as Gavin says the free Let's Encrypt certs are probably fine for most people here. I recommend them to all my clients, and only suggest using paid certs on ecommerce sites or where there is more user data or payment info on required on the site - but that's just
my recommendation, Let's Encrypt certs are absolutely fine and should get an "A" rating on tests like
https://www.ssllabs.com/ssltest/ (
here's one of mine).
Let's Encrypt certs will also satisfy anything Google needs, both in search results and in Chrome.
If you
do want to pay for a cert, Domain Validated (DV) certs are absolutely fine for what you're doing, I certainly wouldn't go any higher if I were you. You're quote: -
is a bit of scare-mongering by someone trying to sell something to you, IMHO.
Remember that, for most websites here, the only security that's a real issue is personal details submitted via an enquiry form. Securing the site via an SSL is fine, nothing can intercept data between the browser and the server, but 99% of these then fire off an email from the web server with all of these submitted details and email is a very insecure method of transmitting anything - but I don't see anyone bleating on about that
Most
decent hosts should now provide a Let's Encrpyt cert for free (I do

). And, again,
that's probably all you need.