Legato literally means"tied together" in Italian and indicates that notes are played smoothly and connected. No silence between notes transitions. With string instruments you mostly use the same bow direction for as many notes as possible while still keeping a desired quality sound. Legato doesn't have to be played in one bow direction but should be made to sound as much so as possible. In notation legato is indicated with a slur, a curved line connecting the notes or by the word itself.
"The richest person is not the one who has the most,
but the one who needs the least."