The use of 'SE'?

[michal]

I don't really understand the use of the word se in some one the cases.
I understand it's a word for activities that happen generally, not necessarily right now, for example: "como se llega a la plaza?".

but here are examples for sentences where I don't understand:

"Esta pelea, puede durar mucho tiempo y termina cuando una de las personas se rinde."

'El turista se le acerca y busca conversar con él. '

what the se is used for? thank you !