The real wordsTheory
The definition, with all three parts
Forward contractAn obligation to buy or sell a certain asset at a specified price (the forward price), at a specified time (the contract maturity or expiration date), typically not traded on an exchange.
Three things are specified: what, at what price, when. Both the buyer and the seller are obligated to fulfil their end at maturity. Neither can walk away because the price moved.
And the line the professor puts on the first slide: no money changes hands until the settlement date.