a character is any living individual/actor featured inside of a scene. these characters can be any living thing but this term usually refers to human actors. the significant of the character can also be widely varied: a character's significance can be anything from the main character of a piece of media with unique traits that set them apart to a background character with no lines or traits. these characters in scripts usually have their own header right in the middle above their dialogue if they have any, stating the name or title of the character.
an action is a term that covers a range of broad things that can be going on inside of the current scene. usually this term refers to what the characters/actors are doing in a given scene at a given time, but may also be events that occur inside the scene (for example an explosion on screen). an action in character terms can be anything as minor as a small gesture or something much bigger/relevant.
the scene number is quite self explanatorily an indicator to keep track which scene the script is for. usually scene numbers can be used as away of ordering scripts and scenes along a clear timeline of what comes first and what comes last: a scene with the number one will probably come before a scene with the number five.
the location in script writing terms refers to where a scene is set. a location can be anything from a small room or a park, but usually is something more specific than just a park or a city so as to let the media producers know exactly where the scene should be. the location is also usually accompanied with two extra bits of information: time of day and interior/exterior. the reason the time of day is mentioned is for lighting purposes and to ensure the correct lighting is used. the int/ext is also added to signify if the area is indoors or outdoors(an interior or exterior).
parentheticals are bits of information put in brackets that usually direct an actor/character on how they should deliver either a particular line or action. this could be discussing their gestures, mannerisms, vocal sound or emotion. a parenthetical allows for scriptwriters to convey how a character is supposed to act like and can go a long way in making a distinct character.
a transition refers to how one scene turns into/goes into another or how one set goes into another without physically having to move the camera from one location to the other. transitions can be varied to make a piece of media have a certain style or can be simple cuts from one scene to another. different transitions can usually be used to create different types of pacing for segments of a media product. a good way to think of a transition is like a bridge between two different scenes to connect them together.
camera shots refers to how a scene is actually taken from the camera. this term encapsulates a lot of elements of cinematography but typically in scriptwriting refers to the angles of a camera and the distance of the camera to the subject. the camera angle can be almost anything, but the most common angles are usually straight ahead or to the side of the subject. the distance can be any form of zoom between a far away shot to an extreme close up
speech is the dialogue spoken by a character. at its most basic level dialogue are words spoken by the actors/characters at a specific scene, but to make good effective dialogue takes a lot of complex thinking and consideration of the characters, their dynamic, the context and emotions.