.Plain is the Page content stripped of HTML tags as a string.
.PlainWords is the Page content stripped of HTML as a []string (string slice). Under the hood, we’re using Go’s strings.Fields to split .Plain into a slice.
.RawContent is the raw content read from the content file. Generally, this would be the raw Markdown content prior to any encoding from Hugo.
plainify is a template function that takes a given input, strips it of HTML tags, and returns a string.
jsonify is a template function that takes a given object, encodes it as JSON, and converts it to HTML-safe content.
The safe* family takes a given input and does a type-casting to the thing you want. For example, safeHTML can take a string as input, but returns a template.HTML type. Go HTML templates are context-aware. If you try to print a string with HTML tags in an HTML context, Go will escape all of the HTML tags. In that case, you need to convert the string type to template.HTML so that Go will leave it alone.