Could someone please tell me what this means in English? Danke!

Literally, "Everything clear?" Similar to "OK?" in American English.

Alles klar, Der Kommisar.

In conversations. it would be used most often when the German speaker is explaining something to you, perhaps in answer to your question. At the end he or she would say, "Alles klar?", "Everything ok? Do you understand? Happy now?"

Alles Klar is also the name of a German-English college level text book.<BR>It usually means as explained above, particularly in the sense that every thing is explained so that it is understood, or at least understandable.<BR>My reaction to some of the book is:<BR>Alles ist gar nicht klar.<BR>In other words, I am not bowled over with the book.<BR>

It is sometimes used literally as explained above - &quot;Do you understand?&quot;, but it's most commonly a &quot;conversation ender&quot; like &quot;okay, then...&quot; and often followed by &quot;Tsch&uuml;ss&quot; (bye-bye).