I'm not sure about Decentraland specifically, but typically there will be a subset of the DAO members who actually control the DAO treasury in a "multisig wallet". Say they have 10 signatories, they might have a requirement that 8 of the 10 signatories approve a transaction to either send ETH to Blender, or do the necessary swaps to give Blender USD. The signatories have committed to execute the will of the DAO.
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)
Voting happens "off chain" using a tool called Snapshot (https://snapshot.org/#/snapshot.dcl.eth). If people hold some Decentraland tokens/assets, they can vote, and their vote is weighted in proportion to their holdings. This isn't without its problems: https://vitalik.ca/general/2021/08/16/voting3.html
If you want to learn more, I wrote a blog post on DAO tooling 101: https://blog.juicebox.money/dao-tooling-101/