Currency refers to how recently a skydiver has jumped. Skills degrade with time away, so drop zones and USPA recommendations set intervals after which a jumper needs a refresher, a check jump, or supervision before jumping normally again.
Why time away matters
Emergency responses need to be automatic, and automatic responses fade. A jumper returning after months away may be perfectly capable in normal circumstances and slow in an abnormal one, which is exactly when speed matters.
Requirements scale with experience and with how long the gap has been — a low-jump-number skydiver away for a season will typically need more than a highly experienced one away a few weeks.
Expect to be asked
Drop zones will ask about your last jump, and to see your logbook and reserve repack date. This is normal and not a judgement on your ability.
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.