Im new to this stuff but i just wanna know if you can display a timer and strean only using xbox
No, you cannot do that. Timers are separate programs, they can’t run when streaming from the Xbox app. You will need a capture card so you can capture the gameplay in something like OBS and then you can build a layout that includes a timer.
Plug in the console and then plug the card into the computer if it’s via USB. If it’s internal then you’ll need to install it into the Motherboard and then plug the console in.
Additionally, they usually have drivers to install that are needed to work. It’s really as simple as that. It can get more complicated than that if you start to get going with splitters and other stuff and split the video signal, but we’d need more info on your setup and capture card of choice.