When you receive a notification that a trade has been queued, it means that your trade order has not yet been executed. This means that, if you had entered an order to buy shares, you are not yet in possession of those shares.
A queued order is still in effect and not yet cancelled or annulled. When your trade is queued, that means continued attempts will be made to execute the order. This does not mean, however, that execution is guaranteed. Despite brokers' later attempts, there is a chance that the order may never be executed.
An order may be queued because you specified it as a market order and other investors have placed the same type of order before you did. In such situations, you must wait until everyone ahead of you gets a successful execution. Assume you wish to buy 100 Apple shares and you placed a market order, which means that the broker will buy Apple at the best possible price, regardless of what that price might be. If, however, market buy orders for a total of a million Apple shares have been placed ahead of you and only half a million Apple shares have been sold since, you will be in queue until other buyers can purchase half a million more shares.
An order may also be queued if it is placed after the close of the stock market and no trades take place after-hours for that particular stock. In this case, you must wait until the markets open on the following business day. The term "after-hours" refers to trading activity that happens outside the regular business hours of the stock exchanges, which is between 9:30 a.m. and 4 p.m. in the United States. Many stocks trade outside of these hours as well, often without interruption for 24 hours a day. If, however, you place an order to trade a stock when the market is closed and there is either no or insufficient after-hours trading activity for that stock, you will be queued until the next business day.
As a general rule, you can cancel queued orders. You do not need to provide a reason for such cancellations, nor do you have to pay a late fee. You can simply change your mind and delete the queued order. However, in a fast-moving market, there is always a chance that your queued order will be executed before you have a chance to cancel it. You should, therefore, never enter a trading order with the hope that it will be queued, assuming you'll therefore have a chance to reassess market conditions in the meantime.