Learn Dutch: Ik hoop dat het klopt. - I hope that it is correct.

The word dat (that) sends the verb to the end of its clause. In dat het klopt, the verb klopt is at the very end. Because this specific clause only has a subject (het) and a verb (klopt), it happens to look like regular word order. If you added more words, they would go before the verb, like dat het precies klopt (that it is exactly correct).

What is the literal meaning of klopt?

The verb kloppen literally means to knock or to beat, like a heart or on a door. However, it is extremely common in everyday Dutch to mean that something is correct, right, or makes sense. You will frequently hear people just say Dat klopt! to mean That is right!

Can I leave out dat the way we often leave out the word that in English?

No. In English you can say I hope it is correct, dropping the connecting word completely. In Dutch, you cannot drop this conjunction. You must always use dat to connect a main clause to a subordinate clause like this.