Eve Online simple question

They are hard to get early in the game. The price of plex keeps going up, so you would need time in game to create easy revenue streams in order to keep buying them. Every plex you buy means that isk can't be invested to make more isk. Once you've been playing for a few months they should be a lot easier to get - depending on how often you play.

There's nothing simple in EvE and if you can't afford the game, you better use that time to make money, cause it takes a lot of time.

You can buy it from the in-game marketplace for money & plenty of guides in the Steam community for Eve Online that might help you or anyone new to the game out.

You would spend far more time grinding the money to buy a PLEX than working 2 hours in real life and paying for your subscription. I played quite a while and I would say it is impossible to play with PLEX when you are starting out. Maybe it's possible when you're all skilled up and have some crazy ship outfits but even then it takes too much time to farm that amount of ISK.

If you dont mind joining some big corp and pvp you should be able to get enough isk(ingame cash) to sustain yourself.

If you want to do it with pve you will have to invest few months to train your character and grind like an hour a day, every day... At least how it was for me few years back.