In Assisted Conversions report, you will find how many conversions were assisted by each channel individually and the overall value for those conversions.
Assisted conversion is the number (and monetary value) of sales and conversions the channel assisted. If a channel appears anywhere except as the final interaction on a conversion path, it is considered an assist for that exact conversion. The higher these numbers get, the more important the assist role of the channel was. To put it in simple words, assisted conversions are the interactions that a customer has with a website leading up to a conversion, but not the final interaction. These Assists are assigned a value based on the transaction they contributed to in order to help assign value to their contribution. It is also important to note that Assisted Conversions values can be higher than total Conversion.
The major takeaway from this is simply that assisted conversions are not a 100% accurate depiction of transactions because values can be attributed to multiple channels for the same transaction. The values are meant to help determine the significance of each channels contribution, not necessarily an accurate picture of sales numbers.