So Hive Dollars according to my @ecency wallet is worth about 4% more than the unit amount. So 1 HBD = 1.04 USD, if we are to believe the numbers in the builtin wallet.
I don't know which exchange @ecency uses but there is but one that is considered by Coin Market Cap, and that is UpBit (1% more than a dollar) and on Hive Engine Hive dollar is said to be worth 3% less than a USD.
Should it get above 5% more than par for some time we could use a collateralised conversion from Hive back into dollars, sell the dollars into Hive until the dollar gets to its correct pricing.
Over on Hivehub.dev, it states the value is 0.9992 USD. Now, I will spend it where it is accepted should the merchant accept it for at least par. If they wont, I will sell for Hive and make it work better. Now the advantage of this 4% premium here is perhaps for a dollar worth of goods you only pay 0.96 HBD. Then it makes more sense to use that than probably anything else.
As for trading, learn the risk. Consider that exchanges have a tendency to forget that you left funds with them or fail to recognize your deposits. They also have a tendency to hold your money for ransom for your private information. Also pretending not to receive your coins. Please don't use CExes. There are DEx alternatives.