To animate a character or prop in a 2D game using Unity, the user needs a sprite sheet with small differences of pose between the sprites. Then they will need to set sprite mode to "multiple" and slice the sheet into the different sprites using the sprite editor with slice mode "grid by cell size" and setting the units as the size of each sprite.
The character/prop will need to be placed in the scene and be able to be visible to see if the movements work. Add an animator component to the character. To apply the animations an animator is added to the object and then a blank animator controller is made in the project window. Next, select all the different frames of the sprite sheet and right-click > create > animation.
Double click on the animator controller and drag the animation into the window, your character will now be animated. Double click on the animation in the animation controller window and tick loop time and your animation will loop.