Can we use both angular material and bootstrap together for a angular project? Is there something that should I know?
Yes, you can. I am doing that in a project right now. But, we started with bootstrap, and then added Material later just to use a few of it's components that don't really look specifically like material design, e.g. the date picker and the autocomplete component.
Given that the two libraries are both collections of UI components and CSS, you're going to have to decide if you want the bootstrap look and feel, or the Material one. I'm not sure if we would have used Bootstrap if we had started with Material Design.
If you want Material, you can probably just go with that - I don't think Bootstrap would get you much extra, unless you just want to use their css grid layout.
If you want the Bootstrap look and feel, there are a few components that either bootstrap does not provide, or where the Material component is subjectively better.