Of course, this isn't really about the status of the Contract so much as the status of getting the Contract signed. It's more technically correct to say it's the Signature Request status, but we'll understand what you mean no matter which one you say!
Once you've sent your Contract to be signed, the Signature Request goes through three stages:
Orange = Sent; your Contract has been sent to a valid email address
Blue = Open; your Contract has been sent and the Signer has opened the link
Green = Completed; your Contract has been sent, opened, and signed by all Signers
If an email is not sent to a valid email address or cannot be delivered, the orange circle will turn red.
Once your Contract has been completed by all Signers, it is available to download. For a deeper dive, check out the doc on Signature Request status.