Deals are offered contracts from a third-party that you can fulfill against payment. You need a Reception Desk and a Receptionist in order to receive and deliver the necessary paperwork and software. All deals, and the amount of deals, are affected by your company's reputation, which can be increased by completing contracts.
There are several different forms of Deals.
Help another company with the design phase of their software.
Help another company with the development of their software.
Take care of another companies support tickets (remove the bugs new users have encountered).
Market another companies software products.
Host software for other companies on your servers. Hosting deals can range from $2.00 per Mbps to $5.00 per Mbps. Also note that you'll have to pay ~$2.00 per Mbps in internet bills. Hosting deals only come if another company releases a software that depends on servers, i.e. website or online game.
Help another company print physical companies of their software (like you do for yourself).
A company offers to buy one of your intellectual properties. Offers will never exceed 1% of the company's total balance, so if an IP is worth too much no companies will offer.