A lead is a visitor's contact details — name, email, phone, and a short note on what they wanted — saved from a conversation with no logged-in user behind it.
Lead capture is available automatically for any anonymous conversation: through an embedded widget or through Telegram. There's nothing to turn on — it isn't a per-assistant setting. The assistant itself decides when to actually save one: once it has a way to follow up (an email or phone number) and a sense of what the person needs, not just because a name came up in conversation.
Saved leads show up on the workspace's Leads page, each one tied back to the assistant, widget (if it came from one), and conversation that captured it — so you can see exactly where it came from and read the conversation it was pulled from.
Capturing a lead doesn't trigger any notification or follow-up on its own — it's a record, not an automated outreach. If you want a notification when a new lead comes in, that's something you'd wire up yourself with a custom tool (e.g. a webhook to your own system).