NIL is an ERC20 Token and can be purchased on the Uniswap decentralized exchange.
Buying on Uniswap
Uniswap is a decentralized exchange that allows for users to swap one token for another. This is a popular way to buy tokens. The first step is to setup a ERC20 Wallet (like Metamask) and deposit tokens (WETH etc) into your ERC20 Wallet. Once you have tokens available in your wallet, you can connect to Uniswap and swap WETH for NIL Tokens.
How Uniswap Works
Uniswap allows anyone the ability to exchange one Ethereum token for another Ethereum token. This is powerful because it not only determines the value of each unique token but allows people to buy and sell their tokens easily with no middleman.
Without getting into the technical side and differences, it works very much like any exchange. You own one asset and want to trade it for another asset. So for example you can swap WETH for NIL.
NIL ensures there is liquidity in the market to allow for people to buy and sell NIL on Uniswap.