get started on (something)
The phrase "get started" simply means "start".
You use "get started on ___" to talk about work that needs to be done:
Do you want me to get started on the salad?
A: Can you pull together a list of all of our clients in that region for the past two years?
B: Of course. I'll get started on that right away!
Just use "start" to talk about ongoing actions:
I need to start exercising.