“Active” listing status means that the property is currently listed for sale
and has not received an accepted offer
. The property is on the market and up for grabs. Sometimes while the status is active the listing agent will already be working with an offer (becoming more common nowadays). The seller may accept an offer and the property says active but it is not available. This happens because the listing agent must manually log into their MLS account and change the status to looking for backup
or pending themselves. Most agents get around to doing it the first day an offer is accepted.