Live action refers to real people playing roles in a live location. Most of what we watch on television or at the movies is live action.
Filmmaking schedules are usually managed around locations. For example, if the beginning of your script is set in a classroom, and the last scene is in the same classroom, you film those scenes together so you aren’t running back and forth to the same locations all day.
Most films are shot and then edited in post-production. This allows the opportunity to film things from a few different angles and try out different edits as well as to learn the skills of editing.
You can film different shots and then edit them together later. Music, sound effects, special effects, and credits are all added to the film in post-production.