Pronouns exist in every language, and German is no exception. Moreover, they are also divided into categories. And possessive pronouns belong to one of these. In German, there is some specificity regarding the use of this part of speech, and it should be studied in more detail.
Basic Rules

This part of speech, also called the Possessivpronomen, is in most cases confronted by certain nouns. Then possessive pronouns in the German language act as definitions. By the way, it should be noted that here everything is about the same as in the case of adjectives - they also necessarily agree with nouns. This refers to gender, case and number. Otherwise, it will not work, because the possessive pronoun indicates the belonging of a certain object to any person. Without agreement with the noun, this part of speech simply cannot be used. Despite some similarities with the Russian language, I must say that there are some differences. For example, if the “book” here refers to the female gender, then in German it is “it,” that is, the middle gender. But many make the mistake of translating all the words literally. You should forget about this and understand that other rules apply in German, and what we might think is illiterate is absolutely normal and generally accepted for German speakers.

Face use
If you deal with this topic, it will turn out much faster to learn German. Possessive pronouns, the table of which is rather small in size, help to better navigate in terms of the use of certain words. It looks something like this:
Ich - mein (I am mine).
Du - dein (you are yours).
Er is sein (he is his).
Sie - ihr (she - her).
Es - sein (him / her).
Wir is unser (we are ours).
Ihr - euer (you are yours).
Sie - Ihr (you are yours).
Remembering possessive pronouns in German is not difficult, just like using them in relation to certain nouns. The only caveat - the ending will be added to them, depending on what kind of word the word belongs to. So, for example, Mein Leben (translation: “my life”) remains unchanged, but Meine Meinung (“my opinion”) is written with the letter “e” at the end. I would like to emphasize the use of possessive pronouns for the third person. Here you need to pay attention to the gender of the noun. In this case, the following rule applies: the male, as well as the middle, gender corresponds to sein. But for women - only ihr.
Case matching
The first thing to note is that in Singular (singular) pronouns change as indefinite articles. But in Plural (plural) - as defined. As an example, take the same word Leben ("life"). If you persuade him in relation to the female gender, then the ending of the noun will change only once (in Genetiv), and it will look like this: ihrem Lebens. The pronouns themselves do not remain unchanged: Nominativ - ihr; Genetiv - ihres; Dativ - ihrem; Akkusativ - ihr. In the case of sein, by the way, declension is performed in a similar way, and endings in nouns remain the same, changing only in the genitive case. This specificity is distinguished by the German language. The declension of possessive pronouns can be easily remembered by learning how their endings change. Since there are only four cases, this is easy to do. Unlike irregular verbs, you do not need to memorize a few hundred words - there is a principle, having understood which, you can apply it to other nouns.
Property designation
In fairness, it is worth noting that possessive pronouns in the German language are quite similar in their usage to the rules in Russian. The only difference is that in German there is no such thing as “your own”. And this applies to all pronouns. Suppose, if you want to say “I have packed my things”, we should use meine (“mine”). It will look like this: ich packte meine Sachen. In translation it will mean the same as in Russian, only meine here replaces the word “svoi”. If it is necessary to say in the plural, that is, “we have gathered our things”, then it will be necessary to use unsere - wir packten Ihre Sachen. Having understood this principle, you can further understand the use of such possessive pronouns on your own (ihr - eure; er - deine; sie - ihre; etc.).
Assimilation of material
To better learn the material, you need to exercise regularly, learning the German language (possessive pronouns). Luckily, there are exercises for this. Of course, the best training is immersion in the language environment, since only by communicating with a native speaker of German, you can fully feel its specificity. But in this case, you can just practice by declining the pronouns in relation to one or another noun. It is best to take one word and change it by cases and persons. It not only helps to understand the topic, it also expands the vocabulary and improves memory. Therefore, regularly training in this way, it will be possible to quickly learn the topic and apply the acquired skills in the future.