@inthehands @GhostOnTheHalfShell @cryptadamist
If you're seeing a single price listed on a stock, that's the per-share price of the last sale on a public exchange. For historical values (like yesterday's price, etc) it's the sale price of the last sale in that period (aka the closing price). If there's not enough volume to give real prices, then your brokerage might just show the open bid (offer to buy) and ask (offer to sell) prices.
This knowledge comes courtesy of building trade ticket UIs for 5+ years at Schwab and Fidelity