As an expression, when people say the 11th hour, they mean that something is done at the last moment. Some similar expressions would be, "last minute" or "in the nick of time". For example, you could say, "he arrived at the train station in the nick of time, just 1 minute before the train left". The expression, "11th" hour, can also mean a desperate, final attempt. For example, you might say, "An eleventh-hour deal was reached by the union representative and the factory owners, so a strike was avoided". Hope this helps

Are you literally referring to the time? It's 11 on the dot. It's 11 o'clock