Need help understanding a wholesale deal

[Mustafa Abdulali]

I came across an ad that a wholesaler put up for a 3/2 in my target area.  He originally wanted an all cash deal but I told him I could not do that but would be willing to finance (I'm already pre-approved).  This property would be my primary residence while I fixed it up with an intent to sell in 2 years.  He told me he would be willing to assign the contract to me for $10K with a sale price of $300K for a total sale of $310K so that I could get conventional financing.  Could someone point me to or explain to me what the "assign a contract" means?  I've never bought from a wholesaler before so I could use some guidance.