Einstein Bot greets your customers, answers their questions, and it can even dip into your fulfillment system and retrieve the customer’s order status. In case the customer does need attention from an actual agent, the bot can smoothly transfer the customer to an available agent, and serve coffee while they are waiting.

Einstein Agent chatbots, built natively on the Salesforce Platform, will allow any company to deliver automatic service at scale using Einstein AI technology.

Using Einstein Chatbot builder, you can easily set it up.

To setup, follow the steps in below link
https://www.infallibletechie.com/2018/06/how-to-setup-einstein-bot-in-salesforce.html 

Using Flow in Einstein Bot
https://www.infallibletechie.com/2020/11/how-to-store-user-entered-values-in.html

How to call Apex from Einstein Chat Bot?
https://www.infallibletechie.com/2019/08/how-to-call-apex-from-einstein-chat-bot.html

SMS Channel – Messaging to Einstein Bot in Salesforce
https://www.infallibletechie.com/2020/10/sms-channel-messaging-to-einstein-bot.html

Einstein Bot getting multiple values from Apex Class
https://www.infallibletechie.com/2020/06/einstein-bot-getting-multiple-values.html

Check the below 2 minutes video
https://youtube.com/watch?feature=youtu.be&v=14l6Blr0jM0

Dialog
Dialogs are conversation snippets that control what your bot can do.

Intent    
Intents are the customer’s reasons for interacting with your bot.

Entity    
An entity represents a type of data that you want to collect from a customer.
Text, DateTime, Date, Money, Number, Person, Location, Organization, Percent, Boolean,
and Object (standard Salesforce or custom)

Variable    
A variable is a container that stores a specific piece of data collected from the customer or output from Salesforce.
The following types are available for custom variables.
Text
Number
Boolean
Object
Date
DateTime
Currency
Id

Add a Bot Profile
Expand a bot’s capabilities and give it access to features like Field Service Lightning by assigning it a custom profile.
Each bot has a Basic Chatbot User profile, but you can create a custom profile and add it to a bot.

Message
Send an outgoing message from your bot to your customer.
A message can be static text or dynamic text from merge fields.
The merge fields reference objects and fields that are currently stored in your bot variables.
The merge field syntax is: {$API_VariableName} or {$API_VariableName.Field}.
Merge context and system variables into bot messages with merge syntax.
{!$System.LastCustomerInput}
{!$Context.ContactId}
{!VariableName}

Question
Gather information from your customer.

Action
Run an autolaunched flow, send email, or use Apex to read, update, or delete Salesforce objects, retrieve data
and display it to the customer, and retrieve external data from a third-party API.

Rules
Specify the conditions that start any of the following actions: call a dialog from within the current dialog,
redirect to a different dialog, clear a variable value, transfer to an agent, and set variables.

Transfer Bot Conversations
1. Use the Transfer to Agent System Dialog to Transfer Conversations.
Transfer conversations to an agent in the queue attached to the Chat deployment defined on the Transfer to Agent dialog.
2. Use the Dialog Rule Element to Transfer Conversations.
a. Transfer Bot Conversations to a Queue
You can route bot conversations to a queue of agents by using the Rule Action Dialog Step.
And, you can help customers who initiates a transfer when agents are offline with the No Available Agents dialog .
b. Transfer Bot Conversations to Another Bot
Create custom solutions in your org by adopting a multi-bot strategy.
Use the Dialog Rule Element to transfer bot conversations to another bot.