MailChimp for Magento takes care of sending all the store information to MailChimp. Then MailChimp is capable of creating awesome campaigns and automations.
Below there is a more detailed list on what each one can do.
If you have any doubt, please create an new thread on our Forum

Mailchimp for Magento Features:

General Features:
    • Send subscribers data
    • Creation of webhooks.
    • Checkout subscription
    • Custom merge vars

Ecommerce Features:

    • Send ecommerce data (orders, customer, products, shopping cart rules).
    • Email Catcher: Show basic popup allowing subscription and saving email for guest abandoned carts if enabled.
Abandoned carts:
    • Send abandoned cart data
    • Link the customer email to the abandoned cart if the guest had enter the email on the popup or on the footer form
    • More information here: Abandoned Carts
Shopping Cart Price Rules:
    • Percent of product price discount
    • Fixed amount discount
    • Fixed amount discount for whole carts
Product type NOT supported: