A wind sock is a fabric cone on a pole at the landing area. It points away from the wind, showing direction, and how fully it inflates gives a rough indication of strength.
Why it matters more than the forecast
Landing into wind reduces ground speed at touchdown. Since surface wind can differ substantially from what was forecast — and from what it was on the previous load — the sock is the live reference.
Some drop zones also use ground arrows or panels to indicate the landing direction in use for that period.
Weather information is not an operational decision
This site shows current conditions on drop zone pages as general context. It is not an indication that jumping is available — the operator makes that call, based on far more than a temperature and wind reading.
These pages explain what things are so the language makes sense. They are not instruction and cannot substitute for it — skydiving is taught in person by rated instructors at a drop zone, and anything involving equipment handling or emergency procedures belongs there rather than on a web page.