Above (in a blue square) you will be able to see live ADA price for 1 ADA in US dollars. For comparison Bitcoin info was added as well since that is best known crypto currency.
Market Cap Rank shows ADA world rank out of all crypto currencies as per market capitalization. There are over 4,000 crypto currencies out there. So, being in top 10 is a big deal. 
​Market Cap is total value of all existing ADA in US dollars. You can think of this as stored value or purchasing power. 
24H Volume is total amount of all ADA transactions in US dollars in last 24 hours. If you spot a crypto coin with constantly low volume compared to Market Cap it probably means it will fail. You can use volume as a signal of use and adaption of digital assets. If it's not moving, then it is of no use to anyone. 

As you can see ADA does not exist in a vacuum. It is part of a large and emerging field of crypto and DeFi. ADA is influenced by general cycles of crypto markets. This is why that scrolling ticker is included in this page. If you see ADA go down in price for a day, check the ticker. If you see a lot of prices on the ticker turn red, that means ADA is just going with market flow. Every sector has cycles and crypto market is no different. 

Want to see how much ADA is in different currency other then US Dollar? ...or how much ADA you need to buy 1 Bitcoin? Below is a handy ADA converter for you to use.