generally in employment means you will do a specific job within certain times frames ex. m-f, 9-5 for a certain amount of restitution. And by showing up daily and accepting the restitution you are fullfilling your part of the contract obligations and the employers is required to fulfill his part by paying you.
When I accept a job at Mc D's, I know what the minimal job requirements are by the listing information. It is my responsibility to get any speceifics in writing. When I sign and review my pay scale, IRS exempt etc, and intial it as being correct, I am accepting an impiled contract.