Please, please, don't just send crypto to an address before you fully understand how it works. Yes, Breadwallet is just a bitcoin wallet. It says so right on their web page. Did you lose your Ether and Litecoin? I hope not. Definitely spend some time learning about this stuff before you lose something valuable. :)

Import private key:

The way Bitcoin (and most cryptocurrencies) function is you have a public key of sorts (your public address) and you have a private key. The private key is what you own and control. That's how you own bitcoin. That import option is if you had a private key from a paper wallet or some other wallet and you wanted to import that private key to your Breadwallet app if you wanted to control the bitcoin at that public address and send it somewhere. It's also what you'd use if you needed to restore your Breadwallet from a backup.