An LST (Liquid Staking Token) is a tradable token that represents staked assets. Think of it like receiving a receipt for your deposit that can be freely traded or used in DeFi.
In native staking, your SOL is locked with validators who secure the network, earning rewards but not being available to trading or spending. LSTs like JupSOL solve this problem by allowing your SOL to remain staked with validators while giving you a liquid token you can use elsewhere. This way, you support network security, earn staking rewards, and keep the flexibility to use your assets in DeFi.