There is a single second person personal pronoun in English (you - and a single associated possessive pronoun your). You / your is the form of address irrespective of whether the addressee is one friend or two friends, one boss or two bosses, one child or two children, one queen or two queens, one dog or two dogs, etc.
German, in contrast, has three second person personal pronouns: du (informal - to one friend, one child, one animal), ihr (informal - to two or more friends, children, animals) and Sie (formal - to one or more adult non-friends). Apart from the fact that it is often difficult for the non-native speaker to know whether to use the formal or informal pronoun with adult acquaintances, each pronoun brings with it its corresponding inflections. Here are all the German equivalents for you / your: du-dich-dir / dein-deine-deiner-deinen-deinem-deines ihr-euch / euer-eure-eurer-euren-eurem-eures Sie-Ihnen / Ihr-Ihre-Ihrer-Ihren-Ihrem-Ihres.
Languages with honorific systems, like Korean, have many more forms of address (each with their corresponding inflections), that depend on the relative status of the person being addressed. This aspect of English grammar is certainly comparatively simple for the ESL learner!