To generate a link to any dashboard, simply click the "Export" button at the top right of that dashboard, then select the "Share Link" option in the drop-down menu.
You'll see your link appear right away. Click the "Copy Link" button to copy that link to your clipboard.
You can then share the link with anyone you like, and they'll instantly have read-only access to that data. The data you share will include all of the metrics and widgets you see on your dashboard or in the report.
All of the links you generate will be permanent, and they'll always show the exact date range you selected when generating the link.
The URL for each link is based on your custom subdomain or custom domain - see here for more information on this.