A sales pipeline is the route a lead travels from first contact to a closed deal, broken into visible stages. In most CRMs, a pipeline is a list of opportunities with a stage, a value, and a date — from "new" to "qualified" to "proposal" to "won." The SDR or BDR fills the top of the pipeline with qualified meetings; the account executive moves them down it. The pipeline is the team's answer to the two questions that decide everything: what's coming, and how much of it will close.
In plain English
Think of the pipeline as a funnel you can look at. A new lead enters the top; each stage filters out the ones that aren't real; the ones that survive become customers. The number of deals in the pipeline, times their value, times your win rate, is roughly your future revenue. That is why a healthy pipeline matters more than any single deal.
Why it matters to you
As an SDR, your whole job is to keep the top of the pipeline full — every qualified meeting you book is one more lead that didn't go cold. As you move up, you'll be measured on the funnel you own, not the one you pass on. When a team says "the pipeline is dry," it means nobody is feeding prospecting or follow-up — and that is the signal to either grind harder or question the role. The pipeline is the honest scoreboard of a sales org.
For knowing when a deal is not worth the effort, see When to Walk Away From a Deal.