If you're completely new, Hypixel Skyblock is most certainly very confusing. Of course there are many people who watch YouTubers play the game, but some don't and are completely lost when they first enter the world of Skyblock. For these people I'm gonna give a short breakdown of what skyblock is about and about the possibilities you have.
Skyblock is most of all normal Minecraft taken to the extremes. You think a stack of diamond blocks is a lot? Meet the enchanted diamond block which requires 25k diamonds to craft and is a material you need multiple of to craft other things. You remember farms in normal Minecraft? Well in this game you don't need food and yet people are building huge 256x256 farms and gain hundreds of thousands of wheat, sugar cane, netherwart an hour. You like enderpearls? This game has a sword that lets you teleport infinetely (as long as you have mana), rendering ender pearls useless as soon as you obtain it.
Another thing that's typical for Skyblock is the exponential increase of power. You start the game with 100 hp, dealing just enough damage to onetap zombies with 100hp (if you know what to buy first). Meanwhile endgame players have almost 4k hp and deal millions of damage. You often times see other players use crazy items you immediately want to have yourself. Like the aspect of the end, Hyperion, Treecapitator, Drills, a flower of truth, ...
Now how do you progress in this game? First of all, the most important thing to do before the introduction of dungeons was grinding skills. There are 8 skills in the game you level up by doing things connected to that skill: Farming, Mining, Combat, Foraging, Enchanting, Fishing, Alchemy (potions) and Taming, as well as 3 cosmetic skills that are not important to level up, Carpentry, Runecrafting and Social. Leveling up the main skills will increase your stats. While skill grinding you can try to unlock and level up collections, granting you access to recipes required to craft powerful items. You do that by simply collecting lots and lots of a certain ressource.
There is also another skill-like system, the slayers. There are 5 slayers in the game, Zombie, Spider, Wolf, Enderman and Blaze. You level these up by beating slayer bosses.
While grinding skills and collections is one way to play the game, it's not the path most players choose. The majority of the playerbase only cares about 2 things: Money and Dungeons.
Almost everything can be a money making method in skyblock, Farming and Mining for example can give you a decent amount of coins, but you could also hunt down rare drops or do some flipping. I'm not gonna get into detail about flipping, but heres a short explanation of what it is: Flipping makes you money by taking small or big risks, investing money or time. You can buy material to craft a certain item and sell it for profit for example. You can buy an item, upgrade it and sell it again. You can try to get underpriced items on the auction house or use buy orders at the bazaar and sell the items you bought immediately via sell orders. If you do it right flipping is by far the best money making method in the game.
Now finally theres dungeons, a randomly generated combat challenge with floors of different difficulties. You have to clear rooms, find secrets and beat a boss to get a boss chest, which can contain crazy rare items that make you a lot of money. You won't immediately be able to do dungeons, as the first floor already requires mid-early game gear. You will die a lot, but as you level up your catacombs skill you will get a huge stat boost in dungeons, getting you to the point where you can finish the floor with ease. In dungeons there are 5 classes you can choose from: Healer, Mage Berserk, Archer and Tank. Your class determines which gear to buy and which stats to prioritize.