links.internal-redirectLinks on the site point at addresses that redirect
Why it matters
When your own links point at an address that redirects, every click costs the visitor an extra round trip before the page starts loading, and every crawl of your site spends a request on the detour. One hop is a small cost, which is why this is only a notice; it is also free to fix, because you control both ends. It builds up after a redesign or a move to https, when the redirects were added and the links were never updated. Google's advice for a site move is to "Change the internal links on the new site from the old URLs to the new URLs", and more generally: "When linking within your site, link to the canonical URL rather than a duplicate URL."
Sources: Site moves with URL changes; How to specify a canonical URL. Google states no ranking cost for a single redirect.
How to fix it
Edit each link to point at the final address. When the link is in a menu, footer or template, one edit fixes it everywhere; for links inside articles, a search-and-replace across the CMS (old address → new address) does the rest. Keep the redirects in place: other sites still link to the old addresses.