Dota is a probably the most complex competitive multiplayer game around, besides some absurdities like EVE online. It's a finely crafted machine designed to give you imense satisfaction or destroy your morale to the lowest levels if you are a mildly competitive guy. it's probably the most "punitive" game ever and every match last for around 30min to a 1h.
So any mistake that you, as a noob, do for not understanding a single skill (every hero has around 4 or more, that can be "combo-ed" too) in a roster of 119 heroes with different roles has, could really impact the game of another 4 players for almost an hour. And that's just the heroes. Besides that, you need to understand at least basically how the majority of the 208 different itens works and how they interact with themselves and those heroes skills above, how the map works, how the MOBA mechanics works, how the game power tempo works (how each hero peaks in power at different times in a game), etc.
After you learn all of this, you need at least a good hand eye coordination close to a mid level RTS player. Considering that you know how a multiplayer RTS works.
And finally, if you juggled with all of this, for the most part you are still dependent of another 4 angry morons to do the same for you to win a game.
That's why the community is unforgiving and toxic as hell. So if you want to try by yourself, watch some videos online an do with bots.
Even with another 4 friends, i would recommend you to begin to play only if they are very calm, zen and like minded. I've seen a fair share of friendships being thrown away with this game.
Today, i would prefer to learn how to fly a fricking F-14 on a simulation like DCS than learn how to play Dota again. It's like a marriage... if you are in, stay in. If you are not, go enjoy your wild life with something else