what is the name of this toolbar i highlighted in red mark? and how to enable it?
p/s: this screenshot is from youtube
It's not a toolbar as such; those are collapsed panels. You can expand/collapse stacks of panels by clicking the tiny double-arrow symbol at the top of the stack, and drag to resize to show the panel name or just the symbol.
If you have a new, default installation of Adobe Illustrator a lot of different features are hidden. You just have to choose the right workspace that works for you. The one pictured in your screen shot is the Essentials Classic workspace. That will bring out that right column of tools. Essentials Classic is the workspace I prefer to start with and then do a bit of customizing.
i got my answer thank you all.