What is compositing?
Photoshop is such an industry standard that "photoshopping" has become a commonly used verb that describes doing photo manipulation work. What we do when we add graphic elements to video content works according to the same principles, only we tend to not use the word "photoshopping," which only applies to stills media.
In the Adobe suite of applications, After Effects is the application to use for this purpose, but for those who do not intend to invest in Adobe applications, DaVinci Resolve's Fusion Page is capable of everything a video producer has to be able to do.
The more correct term to use when describing this kind of work is "compositing," which applies to both stills and video work.
While entirely outside the scope of this programme, this (external) video below gives you an idea of what professional video compositing looks like in the motion graphics industry.
To be clear, you will not be required to do anything like this, so watch it if you find it interesting, otherwise move on! You may not have heard of Nuke before, but it works very similarly to Fusion, so this video works well as an illustration.