Dear friends 👋, here is a simple table on noun declension patterns.
A singular noun in Russian is declined in accordance with its belonging to one of the following three types of declension ⤵️
👉 the 1st declension group (1-е склонение) includes all nouns having the inflexions -а/-я in their Nominative case-forms, most of them being of feminine gender and the other – of masculine (as well as of the so-called 'common' gender, like «коллега»);
👉 the 2nd declension group (2-е склонение) has masculine nouns with no inflexion in their Nominative case-forms (including those ending in the soft sign) and neuter gender nouns;
👉 the 3rd declension group (3-е склонение) includes feminine nouns with no inflexion but ending in the soft sign.
For plural noun endings, please, see photo No.2 (also a simplified version).