se
/se/ · A1 · pron
A reflexive or reciprocal pronoun: oneself, himself, herself, itself, yourself
From Latin se = oneself; the same se hides in English suicide (self-killing)
Latin se meant himself, herself, itself, themselves, and Spanish kept it unchanged. The action bounces back on the doer: se lava = washes himself. With no clear doer it turns impersonal or passive: se habla español = Spanish is spoken.