day trading strategy book

Hello guys, I have a day-trading strategy but I don't understand it very well (cause I am noob)

Can someone with more experience explain?

I look at the Depth of market and Book when I day trade, I usually do it on Poloniex or binance. Those have the book were I can see the time and sale and when the orders get eaten

I have one question: Many times I see BIG ORDERS (10.000) on Ask or on Bid side.

What do these orders mean? Sorry I am noob.

I tought they mean that there are a lot of people willing to buy or to sell at a certein price level

How can a day trader use this information?

The price level with big orders do they mean a strong resistence or support?

What does it mean when these levels get ''eaten'' fast?

For example 10'000 contracts.... one second later you see on the book (ata the same level) ---> 5.000 contracts, then 3000.....then 2000....then 1000

What this does it mean?

For example if there are 10000 contracts on BID side, and these get eaten too fast, what does it mean? The price will go up or lower

Thanks