The terms "operations" and "sales" can be used in many different ways, but every business must deal with these things.
In real estate, operations involves the details of ensuring that your properties are put to their highest and best use, and remain there, generating as much long-term cash-flow/appreciation as possible. This could be the work you do to rehab a property, the work you do to find quality renters, the work you do to keep your renters happy and keep the properties in good condition, the work you do to market and sell your properties, etc.
From a sales perspective, real estate involves ensuring that your assets are generating profits for you -- either cash-flow and/or appreciation. Sales could be the process of renting your properties, selling them, developing them, etc.
Btw, in addition to the things you've mentioned, there are a few other aspects to your business that you I think you need to be comfortable with to ensure success:
- Forecasting Cash-Flow. Many business owners realize that not property forecasting cash-flow can put them in a situation where they can't pay the bills, but they ignore the other end of the spectrum -- without a good cash-flow forecast, you can't grow your business optimally either. To grow your business optimally, you must understand what your cash-flow will look like over a reasonable period into the future.
- Having a Plan. Without a plan, your business is going to run you, and you'll never accomplish your goals. There are different reasons to want to run a business (freedom, feeding your family, personal satisfaction, creating a legacy, building wealth for future generations, etc), and if you don't know what your goals are for running your business, you'll end up building a business that doesn't give you what you need from it.
- Know Your Market. To build a successful business, you need to understand your customers and their needs. But, it's easy to assume that your customers and their needs will be the same next year (and the year after, etc) as they are now. This generally isn't the case. You must constantly have your finger on the pulse of your market, and more importantly, you need to be prepared to change when your market changes.