First question, I will ask a beginner, what's your rating in chess.com? below, 1200? Ok, now it's time to learn upto 2 openings as white as well as black. And stop blundering pieces.
You have crossed 1200? Let's deep dive into calculations, know what is weakness, how to win simple endgame (don't go deep like 3-4 pawns endgame or more). Then what comes is, strategic plans.
Let me tell you my story, how I easily started beating 1400s after stopped playing chess for a month, (and my blitz rating was 1300 that time). (I don't even know my current classical or rapid rating cause I can't focus on the computer screen to calculate deep variations). I took the book How to Reassess your chess to understand other player's game. I completely stopped playing that time. And read the lines Silman wrote carefully, if you understand a position then see what Silman says about that. When you can't get a coach, you just have to study books and some positions from other's game. Before studying middlegame, I suggest to study endgame upto 1700 level if you are over than 1200. In middlegame, you need plan in any kind of position. You gotta learn how to plan from others, if you are a fan of YouTube, visit Levy's video of 2020 (https://www.youtube.com/watch?v=YKEXns2Ed_0, https://www.youtube.com/watch?v=XtaEnxG2lbg&list=PLBRObSmbZluSo6h0AySyeZRdlQzEhr2XL, https://www.youtube.com/watch?v=nm17mDpmBL0&list=PLBRObSmbZluSWzcTDn44GGo1wp4MDDnHb, https://www.youtube.com/watch?v=mCsc24k-Q8M&list=PLBRObSmbZluTCoqlOg-3wEdlyRQLAJ2gs) These few steps are great to take your chess knowledge to next level. The playlist from chessnerd - https://www.youtube.com/playlist?list=PLiEdPeXVPzzGtEyz5RmMFLC4hVPgFXpcQ
Why did I tell to study when you asked why this or that move is good? Let me go straightforward, when you learn how to analyze a position, you automatically knows what happened wrong (but don't tell me that, I am telling you that you can analyze at grandmaster level, also don't tell me, you are at 900 and analyzing them. In the beginning, I said if you are under 1200 just stop blundering nothing else). Suppose, you are an introvert (that's me) and you have a coach and you take group lesson. He generally will teach you what to do in "the position". As an Introvert, you are less likely to ask question, and deep-dive into the board. That's what you can learn from Silman's book, Silman always mentions human-like move. So when you take a position from his book and think what to do, he will tell- what you thought was good or bad (nah, he isn't going to mention 900 ELO move). Silman said, "after completing his book, you can review- what did you understand of a position (this time read answer later)". After completing all these things, you can understand your positions (or even computer sometimes. Sometimes, they are intelligent nonsense).