The female forename Sheila is the English spelling of the Erse SÃ¬le. This is an Irish version of 'Celia'. The name is in common use, particularly in Australia (OED says "predominantly in male use"), as a slang term for 'a young woman, a [potential or actual] girl-friend'. There is an equivalent in the stereotypical slang common noun bruce for a male Australian.
Do not confuse this name with Sheena.