Herr, in German, means <em>mister, sir, gentleman, </em>or in elevated cases, <em>lord</em> or <em>master</em>.
It's important to realize something about German: cases. There are four different cases in German, and they are: nominative - when something acts as a subject <em>(the person doing the action)</em> accusative - when something acts as a direct object <em>(the thing the action happens to)</em> dative - when something acts as an indirect object <em>(like accusative but preceded by to, at, in, etc.)</em> genitive - when something acts as possessing something. <em>(the person to whom something belongs)</em>
Here's a sample sentence. <u>He came into the garage and stole John's bike.</u> The subject, <em>he</em>, is nominative. The direct object, <em>the bike,</em> is accusative. The indirect object, <em>the garage</em>, is dative. The person possessing something, <em>John</em>,<em> </em>is in the genitive.
In English, cases don't matter very much. However, in German they are extremely important. German cases even change how to <u>write and say words<em /></u><em>. (This is called <u>declension</u>.) </em> Herr will appear as Herrn because of its <em>declension</em>. In the nominative, it's <u>Herr</u>. In any other case, it's <u>Herrn</u>. (i.e., when it's acting as the object of a sentence) When it's plural, it's always <u>Herren</u>.