I want to try out speedruning but im wondering if i have to get a timer or something at the side to track my time, or if the admins time runs without timers.

This answer will vary based on the community for the game you are playing, but generally a timer is not required.

Even though a timer is generally not required in the video you submit, you should have some method of timing your run while you’re doing it so you know what time to put in the submission. Mods will retime runs if necessary, but you’ll still need to submit a time with your run.