1. The literal use of bail/bale is to abandon abruptly as in making an emergency exit from an aeroplane in a parachute.
2. The literal meaning of to bail out is to remove water from a leaky boat.
3. It is now more common to use bail in a figurative/metaphorical sense:
The minister has bailed on the government's housing policy (announced his opposition).
The actor bailed on the script (stopped reading his lines with any show of conviction)
4. 'Bail out' is also used metaphorically but usually with a closer connection to the literal meaning: The pilot bailed out of his plane but not Bob has bailed out on us and gone home.
5. The noun is sometimes spelled as one word: bailout.
6. There is a dispute over the spelling of bail and bale - bail is probably used more frequently but both are allowed by most dictionaries.