Seems like
a normal transaction. I assume you purchased around US$13 worth of Bitcoin... the site you bough from, transferred your 0.0018879 BTC to what I am assuming is your address: 1M1ZRPDhaSsPDfTr8JPvUBPFdBzWRw2Lu8
The other value that was sent to the "3" address, is what is known as "change". You can read about it here:
https://en.bitcoin.it/wiki/ChangeYou can read why change gets created here:
https://en.bitcoin.it/wiki/Coin_analogyBitcoin does not work like typical money in a bank... you don't have a balance that you can spend exact amounts from. You have a collection of "coins" all of varying sizes... if they amount you want to send is not exactly the same as a coin you have you'll end up with change.
The transaction output being labelled as "unspent" just means that that particular coin has not been used in a transaction yet. You can see that the output is now "spent" because the output has been used in a subsequent transaction.