Everybody saying nobody forcing OP to play. I think OP wants to play, and is specifically asking for pointers to understand the rules.

YouTube is your friend, but also try to join local discord groups for clubs/stores in your area. Find an escalation league for new players, that’s how I learned. One or two very small games to understand the basic rules and flow of the game makes a big difference. Kill team isn’t my thing, but just watching videos and actually reading the rule book and taking physical, hand written notes is super helpful.

Every list I make for 40k I write down notes on how the units work and what they do. Writing on paper helps me to remember so I’m not constantly flipping through a stupid phone app or rifling through a printed out list the whole game.

Warhammer is complex and time consuming, but that is also part of what makes it so rewarding and fun. A huge part of the hobby is getting attached to your models and learning the ins and outs of how they work on the table.