EVM is "Ethereum Virtual Machine", a similar concept to the JVM "Java Virtual Machine". EVMs are one the most common technology for deployment of arbitrary execution within distributed networks. These kinds of functions and applications are colloquially called smart contracts. The biggest distributed network with this technology being simply called "Ethereum" or "Ethereum mainnet". But any code deployed on Ethereum mainnet is deployable on any other EVM environment, such as Polygon, Avalanche, Binance Smart Chain, Tron, Ethereum Classic, Hashgraph, or Quorum which was stewarded by JP Morgan for a few years for internal enterprise use.
With the other common smart contract network being Tendermint also colloquially referred to as Cosmos.
There are a couple of standard classes with a certain protocol of functions on all these networks. One standardized class is called ERC20, which is a fungible token standard. Deploying this kind of class ensures that you have created an asset with a name, ticker symbol, quantity, and a transfer function. Therefore ERC20 just is a quick way to refer to an additional asset. Assets that represent something the market wants or is familiar with or is redeemable for something the market likes therefore have certain monetary values associated with them. Some communities representing other networks have different protocol names for the same concept, for example, the Binance Smart Chain community has a token standard called BEP20 which is mostly contrived marketing but it could also have tweaks to the ERC20 standard, you have to read them. No different than reading the IETF's REST protocol standard for each function, and then seeing how it is implemented slightly differently across different browsers, devices and frameworks.
DAI is an ERC20 asset that maintains convertibility with $1 US Dollar. It is collateralized by a basket of assets, some completely digital assets and some that are backed by real world assets from centralized issuers.
When it comes to ERC20 naming styles, the market has resorted to prefixes for now.
So on the Secret Network (which uses Tendermint/Cosmos technology instead of EVM), assets that enter it from bridges are called sAssets. So DAI that enters the Secret Network would be sDAI. Where it will inherit the private nature of the network. Specifically the current state of the functions such as quantity, transfer(to, from) would all be unknown from looking at the blockchain.
One of the highest growth areas and highly demanded is in building bridges for assets to move between blockchains. Particularly Liquidity Pool shares and other asset backed derivatives. If you would like to apply yourself here. The market-based rewards are direct, swift, and very high.
More than what FAANG pays their E5's and L5's.
Rust is good too. I'm not too familiar with the Polkadot ecosystem, but the main thing you need to know is that every financial app that has been popular on EVMs needs to be rebuilt on those other ecosystems. There can be multiple of the same things too, no different than multiple grocery stores in a town, or multiple actual bridges. Nothing unique needs to occur, just more. Its literally a global boom town you don't need to go anywhere for and your competition would rather argue about how a MySQL database is better for yield farming than a blockchain.