“Sales have been steadily increasing since the launch.”
You're giving a presentation about the sales results of a product which your company recently started selling. The say this because the company has been selling more and more of the product each week.
Sales have been steadily increasing since the launch.
"Sales" are the number of items you sell or the amount of money you make from selling things:
Sales this quarter are strong.
Sales are down this month.
Sales can be "strong" or "weak", and they can:
- be up
- be down
To "steadily increase" means to keep increasing by the same amount, again and again. Here's an example of some steadily increasing numbers:
20 > 25 > 30 > 36 > 41 > 45
Here are some numbers that are increasing, but not steadily:
20 > 29 > 27 > 28 > 40 > 40
Numbers can also steadily decrease or fall, which means to go down little by little.
This is how to talk about an action that started in the past, and is still happening now:
I've been taking kickboxing classes at my neighborhood gym.
Whenever you use the word "since", you have to use the perfect form "have done":
I've known him since he was born.
We've been ranked #1 every year since 1990.
You shouldn't use the simple past tense ("knew", "were") with "since".
When a rocket "launches", it shoots up into the air. But to "launch" a new product or business means to create it and release it to customers. When you're talking about this event, you call it "a launch".