dejar vs salir (leave)
English 'leave' covers both — dejar is leaving something/someone behind, salir is leaving a place.
dejar
To leave something/someone — you're parting from a person or object, or letting something happen.
Dejó a su novio.
She left her boyfriend.
Leaving a person — ending a relationship. Salir de would mean she physically left him (walked away).
Deja el abrigo en la silla.
Leave the coat on the chair.
Leaving an object somewhere. Never salir for this.
Déjame en paz.
Leave me alone.
Dejar = to let, to leave someone in a state. 'Sal de aquí' would be 'get out of here' — different.
salir
To leave a place — physical departure from a location.
Sale del trabajo a las seis.
He leaves work at six.
Leaving a place. Always salir for departures from locations.
El tren sale a las ocho.
The train leaves at eight.
Departure of transport — always salir.
Salió corriendo.
He ran out / He left running.
Salir + gerund for how someone left. Vivid and common.
Tricky bit
'Dejé el trabajo' = I quit the job (left it behind as a thing). 'Salí del trabajo' = I left the office (physical departure). In English both are 'I left work' — Spanish forces you to decide what you mean.