From the official wiki, "Escape from Tarkov is a hardcore and realistic online first-person action RPG with MMO features." While it has RPG and MMO elements, EFT is a love letter to military sims like ARMA or Operation Flashpoint. Battlestate Games, headquartered in St. Petersberg, Russia, developed EFT as their first game. Tarkov is a fictional city located in the equally fictional region of Norvinsk. Norvinsk is set in Russia, near the border with Europe. After a long period of war, you play as either Russian or European special forces trying to escape from the near-apocalyptic environment.
The Hideout is a feature first launched in late 2019. While it's listed as a "location", and you can technically walk around it in first-person, it's not like other maps. The hideout is a bombed out old shelter, containing a number of stations that allow for crafting, give benefits over time, etc. In a nutshell, upgrading your hideout makes you more powerful and resiliant in the main game.
The crafting stations include the workbench, the lavatory, medstation, and the nutrition unit. New player tip - items crafted in the hideout count as being "found in raid." This can be helpful when you need specific items for quests. While most of the stations are self-explanitory (medstation makes meds, workbench weapons, etc) the lavatory isn't as obvious. The lavatory produces (as of patch 0.12.x) two useful things - a magazine case and (full) fuel tank.
Passive stations provide passive benefits like energy or health regeneration. The passive stations are the air filtering unit, heating system, intelligence center, library, rest space, and water collector. All of these provide either a health/energy/hydration percent bonus or a boost to skills. Passive stations are some of the earliest (heating, water) and latest (library, air filtering) stations that you can build. Another tip for new players - some of the earliest gates you'll face are hydration and health (as you die a lot early). The water collector and medstations are cheap investments that can keep you playing the main game without paying huge amounts of money.
It's important to note that the bonuses from your hideout only apply to your main character, aka your PMC. Scavs, other than getting a reduced cooldown, obviously don't get any benefit from the hideout.
The remaining stations either provide items on a regular basis (free money!) or serve as pre-requisites to building and upgrading. They're pretty easy to understand, so we won't go over them much, but one second-order effect to consider is how they affect item prices. One classic high-ticket item found in raids, the graphics card, is used to power the Bitcoin farm, which makes money over time. As patches come out and changes are made to the hideout, it's worth considering how that will affect item prices on the black market.
There are lots of great guides out there that go way, way more in-depth than I could here. Personally, I focused on getting my Medstation and Workbench up to tier 2 as soon as possible, then took a break. Other improvements, like Stash 2, Intel Center, and Bitcoin Farm are a lot more expensive and difficult to build. Once I have Medstation 2, I can reliably craft myself lots of IFAK kits, which I can either use or sell on the market. You can also use Workbench 2 to breakdown Power Cords into Wires, which generally sell for a little more than the Power Cords would together.
In short, build whatever you're comfortable with. The biggest thing that allowed me to go past Medstation/Lavatory/Workbench into the higher tiers was a Lucky Scav Junkbox, which let me store materials without eating up too much Stash space. Whatever you do, good luck! Let me know if this guide helped you out, or if you have any suggestions. You can find me on Twitter or Reddit.