They don't talk about contracts. They inquire as to availability.
An example. Juve wants Higuain. So they contact Higuain's agent to see if the would be down to move. No money is mentioned. If the player is keen, then Juve contact Madrid as to availability. If the club says, sure we might sell him. Then Juve can go back to the agent with a contract idea. The two clubs negotiate a fee, the fee is accepted and the player looks over the contract. If it's good. Bloom a transfer is born.
Now the issue comes if Real Madrid say no, we do not wish to sell our player, we do not allow you to speak to the player. If Juventus then offer a contract to the agent and continue to press the player, then that is illegal. But it's hard to prove and most of the big teams do it. Chelsea got busted for it a while back with Kalkuta or whatever his name is and they lost a transfer window.
But yeah, most of the "player and club have come to an agreement" and there hasn't been an accepted offer is mostly paper bullshit.