"This is my jacket."
Translation:Ini adalah jaket saya.
"adalah" is the translation of "is" in this sentence, it's optional, so you can omit it if you want
Yes, but I get the feeling that it is used in certain contexts more than others. Is it like Turkish -dir? Is it used specifically in sentences where you define something (I notice the first sentence of a Wikipedia article in Indonesian always uses it) or when you state an objective fact about the world, rather than a personal opinion?