can someone explain marketing automation?

The common ones to start with: a welcome sequence for new subscribers, an abandoned cart email if you sell anything, and a nudge to anyone who went quiet for a couple of months. Most email platforms do all three, Mailchimp and the like. Build one, check it's working, then add the next. People who set up twelve on day one end up with emails contradicting each other.

it's just "if this happens, send that". someone downloads your guide, they get a run of emails over the next fortnight and you never touch it again.