So MineCraft (MC) is a 3D sandbox game, with some adventure and building/crafting mechanics. If we are talking about full PC/java edition, you play it with mouse and keyboard on PC (there are console and other a bit cut-down variant, it’s name is bedrock/pocket edition).
You move 3d model of your character (buttons W A S D), look around with mouse, punch/break items (left mouse click), place/use items (right mouse click). You have inventory (button E) you can craft 2x2 basic recipes inside it, and move around items as in any rpg frome storage to hotbar (1-9) and wear armor on slots you see on you character model (also take some item in off-hand). (Click Esc to open menu, open Controls menu check other controls you might need SPACE jump, Ctrl run, Shift crouch etc)
There are specific interaction blocks like crafting table where you can craft advanced recipes 3x3 (some of crafting recipes you can find in green recipe book when you open crafting interface), furnace for smelting ores etc (other than that you will need to google)
All the world is your pie (it’s almost full freedom sandbox) you can break most blocks and place them in order you need, you can drain liquids (water and lava) and move them around with buckets. There are vertical limitations (from Y 0 to Y 255 pre MC1.18, from Y -64 to Y 320 MC1.18 and forward) and world has defined border (X and Z around 30 million blocks around spawn 0,0 coordinate) There are two other dimensions but that’s advanced thing. For the start I will suggest checking some videos which will show you more advanced stuff.
For adventure part there are 3 bosses End Dragon(end), Elder Guardian(overworld) and Wither(nether), but some you just need to find (Elder Guarian in Ocean Monuments in overworld, End Dragon in end dimension on main island) and some you will need to call (for Wither you need to place 4 soul sand in T shape and 3 wither skulls on top). All of them have their own dangers and issues you will need to work through, and this is advanced for the time you have good armor and weapon. (I will also suggest to check videos)
Another part of Advanture are achievements (button L), there are a lot of them and at least half of them are useful to check out some of game mechanics you might not know about.
There are aggressive mobs you need to fight (in any other mode than peaceful), there are passive mobs you can kill for loot they drop or breed (most of them) and then kill. There are NPC villagers and wandering trader you can interact with and trade items for emerald and emeralds for some other items. (I suggest checking trades as some stuff in 1.17 the easiest to get is from wandering trader, and trading with some farms can replace need for mining for resources, you can even get diamond armor/tools from villagers)
P.S. There is creative mode (e.g. god mode), where you have all the items to chose from and can use as a bock building sandbox. There is also Moded MineCraft (when there are added mods/mod packs to game to improve or completely change mechanics) but that’s another oyster and probably you should check it after you get basics of MC in general.