There are two sets of famous letters in marketing. Each was designed to summarize broad aspects of marketing.
If you read a marketing textbook or take a marketing class, they'll talk about the "Four Ps of Marketing"
* Price, and
Product, in your case, would be your services--having services that are useful; providing the right services for the marketplace.
Place refers to location. Your actual physical location should not be particularly important, compared to that of a retailer. You may even go to clients' offices rather than have them come to your office. Sometimes being in a status office building is an advantage for your image. But it can also make people think you will be too expensive.
Price is a factor in many people's decisions. They can't see your expertise. They can't see your insight. They can't see how your past experience will help you provide solutions for them. They can see price.
Sometimes if you are higher priced, people think that you must be better. But often, high fees will scare prospects away.
When people are making a decision to buy a service, they will make it based on how much they like you or trust you in addition to price.
Actually, the price isn't important if they're sure they're getting benefits worth more to them than the cost. For instance, if you charged $10,000, but saved them $20,000, and they were absolutely sure that was the case, then they'd readily give you the $10,000. Price would be no object. ($5,000, $10,000, $15,000, it wouldn't matter.)
Promotion, in this "4-Ps" summary, refers to all the marketing methods you use. Promotion actually has a more limited meaning in marketing, referring to things like coupons, in-store games, and other techniques to push sales in stores or get people to come in and ask for your brand. But if the people who invented the "4-Ps" used it the correct way, then they wouldn't cover marketing well enough!
A fifth "P" of marketing could be "People" or "Personal" since business goals and objectives need to be in sync with the needs of customers.