A DAO isn't necessarily an "application"; it's more of a concept, an idea.
There are a bunch of tools/applications that facilitate the operation of a DAO. I wrote a blog post about this: https://blog.juicebox.money/dao-tooling-101/
In the case of the JuiceboxDAO, I contributed funds (ETH) to the DAO treasury (bank account), and in return I got $JBX (a token that lives on Ethereum). I have about 40,000 JBX tokens. With these token, I can: - use it to vote on proposals. - "burn it" in exchange for some ETH back (but probably not get my original investment - sell it somewhere else (an automated market maker like Uniswap)