What it is
Summarises the target's TLS configuration from a cached SSL Labs scan: the overall grade, supported protocol versions, forward secrecy, HSTS, and a checklist of historical vulnerabilities including Heartbleed, POODLE, ROBOT, FREAK, LOGJAM and DROWN.
Why it matters
The grade compresses a great deal of judgement into a single letter, and the checklist underneath it is where the detail lives. The scan is cached, so a configuration change made recently may not show up yet.