Trying to understand the bitcoin chart I'm trying to understant this bitcoin chart, but there's no indication of what's the Y axis. The "200K" means the value in dollars? Or in bitcoins? Or what?

I'm trying to check out the value of a bitcoin in comparision with US Dollars over the year.
The left Y-axis applies to the lighter colored volume bars from the bottom of the chart which denote the trading volume in BTC. Alternatively you have the option to display these volume bars in the respective other currency (USD in this case), if you select the "Volume in Currency" checkbox at the left of the page.

A volume bar shows how many units of the currency were traded within the respective timeframe (days in this case).

To just compare the price of Bitcoin in comparison to the US dollar, you can ignore the volume bars and just look at the price as denoted by the Y-axis on the right of the chart. If you use this link, you see just the daily price over a year without volume bars or candlesticks.