A frame is a length of time in which a consecutive image is displayed on a screen. The term can also refer to the image being rendered in this time. The normal framerate of Super Mario 64 is 30 FPS, meaning that 30 frames are rendered on-screen in a single second, but lag can decrease this frequency. Later games have largely adopted a 60 FPS framerate.
Normally, having a button down for two or more consecutive frames will be identified as holding it down, even if the button was pressed separately on each frame. This is unlikely to cause issues in real-time gameplay, but it can prove problematic in tool-assisted speedrunning. Pausing the game will separate these frames without changing any in-game states.
A variable called the global timer increases by 1 on every frame. Some events occur depending on the parity of the global timer, or depending on other functions such as trigonometric calculations, so pause buffering can be used to alter the state of the game.