Se fue

Se fue
 

My understanding is that "se fue" means he/she went away. Is that correct? Fue is the past tense of Ser (to be) correct? So how does se fue become he/she went away?

'Fue' is also the past tense of 'ir'.

Like Rusty said 'fue' is also the past tense of ir but for your example it's just the difference between the verb 'ir' - to go and the pronominal form 'irse' to go away; (él) fue vs (él) se fue.

You usually use ir when you're referring to the place you're going.

Voy a casa. (it's usually used with a, hacía and hasta)

but irse focuses on the action of a person leaving the place where they are, without having to say where the persona is going.

Me voy. I'm going.

Having said that in present tense irse can mean "be about to go (somewhere)"

Me voy al mercado. I'm going (about to go) to the market.