On a project or a customer, Enable portal. You get a Portal link to copy and send.
They see what you choose to show: progress, stages, documents, photos and the updates you post. They do not see your costs, your margin or anything about other customers.
Post an update with a title and details. It appears on their page, and it is the thing that stops "how is it going" phone calls — most of those are somebody with no way to find out.
Turning it off
Turn off kills the page. Regenerate token kills the old link and makes a new one — use it if the link went somewhere it should not have.