What does this Japan Post tracking update mean? Retention and other statuses

Tracking Update Recommended Action
Dispatch from outward office of exchange Nothing! Your shipment is on its way. The next update will be in 4-6 weeks, depending on your delivery address
Retention Contact your local post office for more information
Item held at delivery depot/delivery office Contact your local post office for more information
Item arrival at collection point for pick-up Contact your local post office for more information
Return to sender Contact our support team to confirm your options