The best way to learn is to do, according to my experience. I've worked for a number of bands that have never played before (with players aged 11 to 56 (!!)) and, in my experience, they really have misunderstanding the game until they play it.
The first step is to give everyone a character sheet – if they are really lost, create one for them, or get one already made online. There are many numbers in a character sheet that are confusing when you do not know what they are for.
The second step is simply to play. That's all. Tell them that the basic concept of the game is that they say what they want to do and that you will tell them how it goes, and that they might need to roll dice for the game. determine.
I like to start with simple things. In my one-shot with the new players, I just asked them to participate directly in a single fight, and let them go, since that was all they would do during the one-shot. During my long campaign, I created a small "tutorial level", allowing my players to walk around the city a bit, shop and do a minor role-playing game, and then participate in a small battle where everyone had the chance to make some attack rolls and be attacked in turn.
People will (usually) understand the game while you play. (I say in general, because I play with a friend who often plays the clergy, and she still does not know how the spellcasting works.) I think the best way is to get rid of the explanation as much as you can. can, and just throw them all in.
The other thing that really helps (but you can not really get them to do it) is to listen or watch others play. Even loose rule podcasts always give a general idea of how the game works. I found it very useful for my abilities and my confidence as a new player, and there is a clear difference between my players who listened or watched the DND campaigns and those who did not do it.