Why broken links matter
Every dead link is a visitor who hits a wall, and a signal to Google that the site isn't looked after. Broken images make service pages look abandoned, and broken scripts can stop booking or contact forms working.
How to fix them
Update the link to the right page, remove it, or set up a permanent (301) redirect from the old address. For redirects, point links straight at the final address to save a hop.
"Blocked by site"
Some websites (often social networks) refuse automated checks. Those links are usually fine; open them in your browser to be sure.