Latest is the superlative of late.
You use latest to describe something that is the most recent thing of its kind.
her latest book.
她最近出版的书。
You can use latest to describe something that is very new and modern and is better than older things of a similar kind.
Crooks are using the latest laser photocopiers to produce millions of fake banknotes.
骗子们用最新型的激光影印机制作出了上百万的假钞。
I got to drive the latest model.
我得以驾驶最新式的车。
at the latest
You use at the latest in order to indicate that something must happen at or before a particular time and not after that time.
She should be back by ten o'clock at the latest.
她最晚应该在10点钟回来。