Your chip deck is what contains all your chips used for battling. At the "head" of the deck (The middle left-most spot) is your navi chip, which is what partially determines your maximum MB and HP, in addition to upgrades. See How does the battle system work? for more information on how chip placement within the chip affects battling.
Chip priority is a hidden property of every chip that decides which chip goes first. Elemental chips always have a higher priority than normal element chips. If the chips both have the same priority, random chance chooses which one is used first.
Turns that you would have gained but didn't because you already had the maximum number are called "lost turns." There is no point to knowing your lost turns except to show you how many turns you missed out on. Ideally, it is preferrable to keep your lost turns to a mininum. Donators can buy back their lost turns for 1000z per turn.
MB is a property that every chip has that determines what can fit into your deck. When you add the MB of all the chips in your deck together, it must be below your MB limit. You can increase your MB limit by buying upgrades or changing NaviChips, but you cannot decrease the MB of a chip. Generally, stronger chips have higher MB, but this is not always the case. You can check the MB of a chip in the chip library
Your sack is where you can store literally tons of chips. It can hold up to 99 of each type of chip. Any chips you win in battle or buy from the shop will show up here. However, you can only transfer chips between your sack and your folder (Doable via the Folder menu option), you cannot transfer directly to your deck. In addition, you cannot access your sack for 1 hour after battling.
Turns are used up when you battle or use the lottery. If you don't have enough turns you can't battle. You regain turns at a rate of one per hour, with a limit of 20. Turns that you would have gained but didn't because you already had the maximum number are called "lost turns."