Market depth shows the number of open buy and sell orders for a coin at different prices. It helps to measure the amount of crypto that must be traded before a price moves.
The lines show how many crypto would need to be bought or sold to reach a given price point.
The green line is cumulative buy orders below the current price if you have coins to sell, they will buy them from you. The red line is cumulative sell orders above that price if you want to buy coins, they will sell them to you.
There are also vertical lines — these are buy walls and sell walls. For the price to keep going up or down through that wall, the order has to be fully satisfied.
The market depth chart also gives you an indication whether the price will most likely move up or down. As a rule of thumb if buy orders outweigh sell orders, price might increase.