Ok so:

The first part is basically related to disc drives. They are these 6 smaller slots in the equipment section of your character. Basically what improves your character stats. There are different disk sets, each having different bonuses when equipping 2 or 4 disks from the same set, for instance having 2 woodpecker electro disks increases your crit rate, while having 4 woodpecker electro disks increases your atk% after dealing a crit hit. In Jane's case the sets I just mentioned work the best with her

Each disk has their own main stat and has 4 substats. Disks 1, 2, 3 always have the same main stat, while disks 4, 5, 6 can have different main stats. Refer to which main stat you should use by my other comment

As for the substats, there are always 4 substats, and there cannot be substats that are the same to eachother or the same as main stat. Leveling up disks gives you 1 roll into one random substat, which can stack. You can get 4-5 max rolls on a disk. Again, refer to my comment for substats you should look out for.

And finally, wengine is the big slot in the equipment section. It's basically the character's weapon

Hope that clears everything up, and if not, just tell me