Editing a selection of frames?

So I’ve been animating in toonboom for around a month and a half now and have been having a great time making animations, but one thing that is constantly bothering me is trying to edit a selection of frames/keyframes/pegs. for a long time I’ve been researching how to edit a selection of frames without editing everything in the layer or more or something like that and whenever I searched up how to do that it would bring me to keyframes and pegs and despite trying to figure it out I have basically no idea how they work, it would be great if I could get some help on how these things work exactly cause despite seeing a good handful of things relating to them I am still completely stumped and it makes me feel like there’s way too much of toonboom I don’t understand. Can anyone give me a concise explanation of pegs/keyframes for the point of view of someone who has no clue on how these specific things work?
also what are these “Extracranial Germ Cell Tumor, Childhood +91-9783777879 disease Chakdaha” posts

Sorry if I’m being annoying but could I please get an answer? I had a entire animation for school ruined because I didn’t understand how these things worked and I would like to prevent this from happening in the future